I'm writing an Excel spreadsheet with Python's xlwt and I need numbers to be formatted using "." as thousands separator, as it is in brazilian portuguese language. I have tried: style.num_format_str = r'#,##0' And it sets the thousands separator as ','. If I try setting num_format_str to '#.##0', I'll get number formatted as 1234.000 instead of 1.234. And if I open document in OpenOffice and format cells, I can set the language of the cell to "Portuguese (Brazil)" and then OpenOffice will show the format code as being "#.##0", but I don't find a way to set the cell's language to brazilian portuguese. Any ideas?