New Post: PHPExcel convert XLS to CSV with special characters

The spreadsheet content will be saved in the CSV file encoded as UTF-8

Optionally, you can tell the CSV Writer to write a BOM as well

$writer->setUseBOM(true);

But it's up to the applications reading that file to treat it correctly as UTF-8 data. Applications like MS Excel itself should handle it properly, but text editors like notepad won't recognise the UTF-8 data.