<?
header ("Expires: Mon, 26 Jul 1997 05:00:00 GMT");  
header ("Last-Modified: " . gmdate("D,d M YH:i:s") . " GMT");  
header ("Cache-Control: no-cache, must-revalidate");  
header ("Pragma: no-cache");  
header ("Content-type: application/x-msexcel");  
header ("Content-Disposition: attachment; filename=\"prueba.xls\"" );

echo "uno\tdos\ttres\tcuatro\tcinco\tseis\t\n";
echo "siete\tocho\tnueve\tdiez\tonce\t4\t\n";
echo "doce\ttrece\tcatorce\tquince\t46\tah\t\n";
?>

Downloadable Excel File with PHP

php, excel

PHP