<?php
 
	define('MAGENTO', realpath(dirname(__FILE__)));
	require_once MAGENTO . '/app/Mage.php';
	Mage::app();
 
	$category = Mage::getModel ( 'catalog/category' );
	$tree = $category->getTreeModel ();
	$tree->load ();
 
	$ids = $tree->getCollection ()->getAllIds ();
 
	if ($ids) {
		$file = "var/import/catwithid.csv";
		file_put_contents($file,"catId, catName\n");
		foreach ( $ids as $id ) {
		  $string = $id . ', ' .$category->load($id)->getName() . "\n";
			file_put_contents($file,$string,FILE_APPEND);
		}
	}
?>

http://www.sonassi.com/knowledge-base/quick-script-to-export-categories-with-ids/

Simply save the above code in a PHP file in the base Magento directory of your store, and visit the URL in your web browser, simples!

Export categories with ID's

magento

PHP