nested_levels = root.split('\\')
    if len(nested_levels) == 2:

Thank you very much, I will use your solution.

I just found another solution here :
http://stackoverflow.com/questions/17493271/limit-the-number-of-nested-directories-traversed-by-os-walk

Here is my code, maybe it will helps someone else with a different need.

import os;
import sys;
Path="C:\\python-test"
for root, dirs, files in os.walk(Path):
	nested_levels = root.split('/')
	if len(nested_levels) > 0:
		del dirs[:]
	for filename in files:		
		if filename[-5:] == '.html':
			notepad.open(root + "\\" + filename)
			console.write(root + "\\" + filename + "\r\n")
			notepad.runMenuCommand("Encodage", "Convertir en UTF-8")
			notepad.save()
			notepad.close()

Perhaps the quickest way to modify it to do what you want would be adding a single line below the os.walk() line:

for root, dirs, files in os.walk(Path):
    if root == Path:

import os;
import sys;
Path="C:\\python-test"
for root, dirs, files in os.walk(Path):
	for filename in files:		
		if filename[-5:] == '.html':
			notepad.open(root + "\\" + filename)
			console.write(root + "\\" + filename + "\r\n")
			notepad.runMenuCommand("Encodage", "Convertir en ANSI")
			notepad.save()
			notepad.close()

Results:
(I want to exclude : files in subdirectories below python-test folder)

C:\python-test\fichier1.html
C:\python-test\fichier2.html
C:\python-test\python-folder\fichier3.html

I was looking for a way to do it in NPP. I found a solution with a Python script (see below) but I’m looking for a way to limit the depth of os.walk method. I want to apply the conversion to HTML files located in the first level only, excluding those in subdirectories. Can someone help on this? Thanks.

https://pw999.wordpress.com/2013/08/19/mass-convert-a-project-to-utf-8-using-notepad/

Maxim

https://sourceforge.net/projects/cp-converter/