DME has been considered to be a new alternative fuel for direct fuel cells. However, there is little knowledge about the electro-oxidation mechanism of the DME oxidation reaction (DOR). It is very important to know the intermediate adsorption species of the DOR on the Pt catalysts for verifying the DOR mechanism and developing more active catalysts in order to improve the performance of the direct DME fuel cell (DDMEFC). The electro-oxidation activity, coverage of the adsorption species, types of the intermediate adsorption species, and the fractional coverage of the linear-Co-ad (COL) of the DOR as the function of potential and scan rate were studied and compared with that of the methanol oxidation reaction (MOR). It was found that the coverage of the adsorption species (theta(ads)) was ca. 90% for the DOR at 0.1 < E < 0.45 V on the Pt. The fractional coverage of COL formed in the DOR decreased with the decrease in the potential from 0.4 to 0.1 V. It was larger than 50% at 0.3 < E < 0.5 V. The COL would be the dominant adsorption species for the DOR. Except the COL, the intermediate adsorption species of the DOR were the bridge-COad (COB), -COOH, -CHO, -HCOO- and -OCH3. (C) 2007 Published by Elsevier Ltd.