diff --git a/py/util.go b/py/util.go
index 56558cac..e2904187 100644
--- a/py/util.go
+++ b/py/util.go
@@ -7,6 +7,7 @@ package py
 import (
 	"errors"
 	"strconv"
+	"strings"
 )
 
 var (
@@ -204,3 +205,32 @@ func loadValue(src Object, data interface{}) error {
 	}
 	return nil
 }
+
+// Println prints the provided strings to gpython's stdout.
+func Println(self Object, args ...string) bool {
+	sysModule, err := self.(*Module).Context.GetModule("sys")
+	if err != nil {
+		return false
+	}
+	stdout := sysModule.Globals["stdout"]
+	write, err := GetAttrString(stdout, "write")
+	if err != nil {
+		return false
+	}
+	call, ok := write.(I__call__)
+	if !ok {
+		return false
+	}
+	for _, v := range args {
+		if !strings.Contains(v, "\n") {
+			v += " "
+		}
+		_, err := call.M__call__(Tuple{String(v)}, nil)
+		if err != nil {
+			return false
+		}
+
+	}
+	_, err = call.M__call__(Tuple{String("\n")}, nil) // newline
+	return err == nil
+}
diff --git a/stdlib/os/os.go b/stdlib/os/os.go
new file mode 100644
index 00000000..d863575f
--- /dev/null
+++ b/stdlib/os/os.go
@@ -0,0 +1,228 @@
+// Copyright 2022 The go-python Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package os implements the Python os module.
+package os
+
+import (
+	"os"
+	"os/exec"
+	"runtime"
+	"strings"
+
+	"github.com/go-python/gpython/py"
+)
+
+var (
+	osSep     = py.String("/")
+	osName    = py.String("posix")
+	osPathsep = py.String(":")
+	osLinesep = py.String("\n")
+	osDefpath = py.String(":/bin:/usr/bin")
+	osDevnull = py.String("/dev/null")
+
+	osAltsep py.Object = py.None
+)
+
+func initGlobals() {
+	switch runtime.GOOS {
+	case "android":
+		osName = py.String("java")
+	case "windows":
+		osSep = py.String(`\`)
+		osName = py.String("nt")
+		osPathsep = py.String(";")
+		osLinesep = py.String("\r\n")
+		osDefpath = py.String(`C:\bin`)
+		osDevnull = py.String("nul")
+		osAltsep = py.String("/")
+	}
+}
+
+func init() {
+	initGlobals()
+
+	methods := []*py.Method{
+		py.MustNewMethod("getcwd", getCwd, 0, "Get the current working directory"),
+		py.MustNewMethod("getcwdb", getCwdb, 0, "Get the current working directory in a byte slice"),
+		py.MustNewMethod("chdir", chdir, 0, "Change the current working directory"),
+		py.MustNewMethod("getenv", getenv, 0, "Return the value of the environment variable key if it exists, or default if it doesn’t. key, default and the result are str."),
+		py.MustNewMethod("getpid", getpid, 0, "Return the current process id."),
+		py.MustNewMethod("putenv", putenv, 0, "Set the environment variable named key to the string value."),
+		py.MustNewMethod("unsetenv", unsetenv, 0, "Unset (delete) the environment variable named key."),
+		py.MustNewMethod("_exit", _exit, 0, "Immediate program termination."),
+		py.MustNewMethod("system", system, 0, "Run shell commands, prints stdout directly to deault"),
+	}
+	globals := py.StringDict{
+		"error":   py.OSError,
+		"environ": getEnvVariables(),
+		"sep":     osSep,
+		"name":    osName,
+		"curdir":  py.String("."),
+		"pardir":  py.String(".."),
+		"extsep":  py.String("."),
+		"altsep":  osAltsep,
+		"pathsep": osPathsep,
+		"linesep": osLinesep,
+		"defpath": osDefpath,
+		"devnull": osDevnull,
+	}
+
+	py.RegisterModule(&py.ModuleImpl{
+		Info: py.ModuleInfo{
+			Name: "os",
+			Doc:  "Miscellaneous operating system interfaces",
+		},
+		Methods: methods,
+		Globals: globals,
+	})
+}
+
+// getEnvVariables returns the dictionary of environment variables.
+func getEnvVariables() py.StringDict {
+	vs := os.Environ()
+	dict := py.NewStringDictSized(len(vs))
+	for _, evar := range vs {
+		key_value := strings.SplitN(evar, "=", 2) // returns a []string containing [key,value]
+		dict.M__setitem__(py.String(key_value[0]), py.String(key_value[1]))
+	}
+
+	return dict
+}
+
+// getCwd returns the current working directory.
+func getCwd(self py.Object, args py.Tuple) (py.Object, error) {
+	dir, err := os.Getwd()
+	if err != nil {
+		return nil, py.ExceptionNewf(py.OSError, "Unable to get current working directory.")
+	}
+	return py.String(dir), nil
+}
+
+// getCwdb returns the current working directory as a byte list.
+func getCwdb(self py.Object, args py.Tuple) (py.Object, error) {
+	dir, err := os.Getwd()
+	if err != nil {
+		return nil, py.ExceptionNewf(py.OSError, "Unable to get current working directory.")
+	}
+	return py.Bytes(dir), nil
+}
+
+// chdir changes the current working directory to the provided path.
+func chdir(self py.Object, args py.Tuple) (py.Object, error) {
+	if len(args) == 0 {
+		return nil, py.ExceptionNewf(py.TypeError, "Missing required argument 'path' (pos 1)")
+	}
+	dir, ok := args[0].(py.String)
+	if !ok {
+		return nil, py.ExceptionNewf(py.TypeError, "str expected, not "+args[0].Type().Name)
+	}
+	err := os.Chdir(string(dir))
+	if err != nil {
+		return nil, py.ExceptionNewf(py.NotADirectoryError, "Couldn't change cwd; "+err.Error())
+	}
+	return py.None, nil
+}
+
+// getenv returns the value of the environment variable key.
+// If no such environment variable exists and a default value was provided, that value is returned.
+func getenv(self py.Object, args py.Tuple) (py.Object, error) {
+	if len(args) < 1 {
+		return nil, py.ExceptionNewf(py.TypeError, "missing one required argument: 'name:str'")
+	}
+	k, ok := args[0].(py.String)
+	if !ok {
+		return nil, py.ExceptionNewf(py.TypeError, "str expected (pos 1), not "+args[0].Type().Name)
+	}
+	v, ok := os.LookupEnv(string(k))
+	if ok {
+		return py.String(v), nil
+	}
+	if len(args) == 2 {
+		return args[1], nil
+	}
+	return py.None, nil
+}
+
+// getpid returns the current process id.
+func getpid(self py.Object, args py.Tuple) (py.Object, error) {
+	return py.Int(os.Getpid()), nil
+}
+
+// putenv sets the value of an environment variable named by the key.
+func putenv(self py.Object, args py.Tuple) (py.Object, error) {
+	if len(args) != 2 {
+		return nil, py.ExceptionNewf(py.TypeError, "missing required arguments: 'key:str' and 'value:str'")
+	}
+	k, ok := args[0].(py.String)
+	if !ok {
+		return nil, py.ExceptionNewf(py.TypeError, "str expected (pos 1), not "+args[0].Type().Name)
+	}
+	v, ok := args[1].(py.String)
+	if !ok {
+		return nil, py.ExceptionNewf(py.TypeError, "str expected (pos 2), not "+args[1].Type().Name)
+	}
+	err := os.Setenv(string(k), string(v))
+	if err != nil {
+		return nil, py.ExceptionNewf(py.OSError, "Unable to set enviroment variable")
+	}
+	return py.None, nil
+}
+
+// Unset (delete) the environment variable named key.
+func unsetenv(self py.Object, args py.Tuple) (py.Object, error) {
+	if len(args) != 1 {
+		return nil, py.ExceptionNewf(py.TypeError, "missing one required argument: 'key:str'")
+	}
+	k, ok := args[0].(py.String)
+	if !ok {
+		return nil, py.ExceptionNewf(py.TypeError, "str expected (pos 1), not "+args[0].Type().Name)
+	}
+	err := os.Unsetenv(string(k))
+	if err != nil {
+		return nil, py.ExceptionNewf(py.OSError, "Unable to unset enviroment variable")
+	}
+	return py.None, nil
+}
+
+// os._exit() immediate program termination; unlike sys.exit(), which raises a SystemExit, this function will termninate the program immediately.
+func _exit(self py.Object, args py.Tuple) (py.Object, error) { // can never return
+	if len(args) == 0 {
+		os.Exit(0)
+	}
+	arg, ok := args[0].(py.Int)
+	if !ok {
+		return nil, py.ExceptionNewf(py.TypeError, "expected int (pos 1), not "+args[0].Type().Name)
+	}
+	os.Exit(int(arg))
+	return nil, nil
+}
+
+// os.system(command string) this function runs a shell command and directs the output to standard output.
+func system(self py.Object, args py.Tuple) (py.Object, error) {
+	if len(args) != 1 {
+		return nil, py.ExceptionNewf(py.TypeError, "missing one required argument: 'command:str'")
+	}
+	arg, ok := args[0].(py.String)
+	if !ok {
+		return nil, py.ExceptionNewf(py.TypeError, "str expected (pos 1), not "+args[0].Type().Name)
+	}
+
+	var command *exec.Cmd
+	if runtime.GOOS != "windows" {
+		command = exec.Command("/bin/sh", "-c", string(arg))
+	} else {
+		command = exec.Command("cmd.exe", string(arg))
+	}
+	outb, err := command.CombinedOutput() // - commbinedoutput to get both stderr and stdout -
+	if err != nil {
+		return nil, py.ExceptionNewf(py.OSError, err.Error())
+	}
+	ok = py.Println(self, string(outb))
+	if !ok {
+		return py.Int(1), nil
+	}
+
+	return py.Int(0), nil
+}
diff --git a/stdlib/os/os_test.go b/stdlib/os/os_test.go
new file mode 100644
index 00000000..8ae63d09
--- /dev/null
+++ b/stdlib/os/os_test.go
@@ -0,0 +1,15 @@
+// Copyright 2022 The go-python Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package os_test
+
+import (
+	"testing"
+
+	"github.com/go-python/gpython/pytest"
+)
+
+func TestOs(t *testing.T) {
+	pytest.RunScript(t, "./testdata/test.py")
+}
diff --git a/stdlib/os/testdata/test.py b/stdlib/os/testdata/test.py
new file mode 100644
index 00000000..100f48df
--- /dev/null
+++ b/stdlib/os/testdata/test.py
@@ -0,0 +1,121 @@
+# Copyright 2022 The go-python Authors.  All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+import os
+
+print("test os")
+print("os.error: ", os.error)
+print("os.getenv($GPYTHON_TEST_HOME)=", os.getenv("GPYTHON_TEST_HOME"))
+os.putenv("GPYTHON_TEST_HOME", "/home/go")
+print("os.environ($GPYTHON_TEST_HOME)=", os.environ.get("GPYTHON_TEST_HOME"))
+print("os.getenv($GPYTHON_TEST_HOME)=", os.getenv("GPYTHON_TEST_HOME"))
+os.unsetenv("GPYTHON_TEST_HOME")
+print("os.unsetenv($GPYTHON_TEST_HOME)=", os.getenv("GPYTHON_TEST_HOME"))
+
+if not os.error is OSError:
+    print("os.error is not OSError!")
+else:
+    print("os.error is OSError [OK]")
+
+## FIXME(sbinet): check returned value with a known one
+## (ie: when os.mkdir is implemented)
+if os.getcwd() == None:
+    print("os.getcwd() == None !")
+else:
+    print("os.getcwd() != None [OK]")
+
+## FIXME(sbinet): check returned value with a known one
+## (ie: when os.mkdir is implemented)
+if os.getcwdb() == None:
+    print("os.getcwdb() == None !")
+else:
+    print("os.getcwdb() != None [OK]")
+
+print("os.system('echo hello')...")
+if os.name != "nt":
+    os.system('echo hello')
+else: ## FIXME(sbinet): find a way to test this nicely
+    print("hello\n")
+
+if os.getpid() > 1:
+    print("os.getpid is greater than 1 [OK]")
+else:
+    print("invalid os.getpid: ", os.getpid())
+
+orig = os.getcwd()
+testdir = "/"
+if os.name == "nt":
+    testdir = "C:\\"
+os.chdir(testdir)
+if os.getcwd() != testdir:
+    print("invalid getcwd() after os.chdir:",os.getcwd())
+else:
+    print("os.chdir(testdir) [OK]")
+os.chdir(orig)
+
+try:
+    os.chdir(1)
+    print("expected an error with os.chdir(1)")
+except TypeError:
+    print("os.chdir(1) failed [OK]")
+
+try:
+    os.environ.get(15)
+    print("expected an error with os.environ.get(15)")
+except KeyError:
+    print("os.environ.get(15) failed [OK]")
+
+try:
+    os.putenv()
+    print("expected an error with os.putenv()")
+except TypeError:
+    print("os.putenv() failed [OK]")
+
+try:
+    os.unsetenv()
+    print("expected an error with os.unsetenv()")
+except TypeError:
+    print("os.unsetenv() failed [OK]")
+
+try:
+    os.getenv()
+    print("expected an error with os.getenv()")
+except TypeError:
+    print("os.getenv() failed [OK]")
+
+try:
+    os.unsetenv("FOO", "BAR")
+    print("expected an error with os.unsetenv(\"FOO\", \"BAR\")")
+except TypeError:
+    print("os.unsetenv(\"FOO\", \"BAR\") failed [OK]")
+
+if bytes(os.getcwd(), "utf-8") == os.getcwdb():
+    print('bytes(os.getcwd(), "utf-8") == os.getcwdb() [OK]')
+else:
+    print('expected: bytes(os.getcwd(), "utf-8") == os.getcwdb()')
+
+golden = {
+        "posix": {
+            "sep": "/",
+            "pathsep": ":",
+            "linesep": "\n",
+            "devnull": "/dev/null",
+            "altsep": None
+        },
+        "nt": {
+            "sep": "\\",
+            "pathsep": ";",
+            "linesep": "\r\n",
+            "devnull": "nul",
+            "altsep": "/"
+        },
+}[os.name]
+
+for k in ("sep", "pathsep", "linesep", "devnull", "altsep"):
+    if getattr(os, k) != golden[k]:
+        print("invalid os."+k+": got=",getattr(os,k),", want=", golden[k])
+    else:
+        print("os."+k+": [OK]")
+
+print("OK")
diff --git a/stdlib/os/testdata/test_golden.txt b/stdlib/os/testdata/test_golden.txt
new file mode 100644
index 00000000..8aae577d
--- /dev/null
+++ b/stdlib/os/testdata/test_golden.txt
@@ -0,0 +1,27 @@
+test os
+os.error:  <class 'OSError'>
+os.getenv($GPYTHON_TEST_HOME)= None
+os.environ($GPYTHON_TEST_HOME)= None
+os.getenv($GPYTHON_TEST_HOME)= /home/go
+os.unsetenv($GPYTHON_TEST_HOME)= None
+os.error is OSError [OK]
+os.getcwd() != None [OK]
+os.getcwdb() != None [OK]
+os.system('echo hello')...
+hello
+
+os.getpid is greater than 1 [OK]
+os.chdir(testdir) [OK]
+os.chdir(1) failed [OK]
+os.environ.get(15) failed [OK]
+os.putenv() failed [OK]
+os.unsetenv() failed [OK]
+os.getenv() failed [OK]
+os.unsetenv("FOO", "BAR") failed [OK]
+bytes(os.getcwd(), "utf-8") == os.getcwdb() [OK]
+os.sep: [OK]
+os.pathsep: [OK]
+os.linesep: [OK]
+os.devnull: [OK]
+os.altsep: [OK]
+OK
diff --git a/stdlib/stdlib.go b/stdlib/stdlib.go
index 8182d462..d69268d3 100644
--- a/stdlib/stdlib.go
+++ b/stdlib/stdlib.go
@@ -21,6 +21,7 @@ import (
 	_ "github.com/go-python/gpython/stdlib/binascii"
 	_ "github.com/go-python/gpython/stdlib/builtin"
 	_ "github.com/go-python/gpython/stdlib/math"
+	_ "github.com/go-python/gpython/stdlib/os"
 	_ "github.com/go-python/gpython/stdlib/string"
 	_ "github.com/go-python/gpython/stdlib/sys"
 	_ "github.com/go-python/gpython/stdlib/time"