In this paper we report a surface science study aimed at fundamental understanding of supporting Pt on the surfaces of tungsten carbides. The reaction pathways of methanol, water, and carbon monoxide over platinum-modified C/W (110) surfaces are studied using temperature-programmed desorption (TPD), high-resolution electron energy loss spectroscopy (HREELS), and Auger electron spectroscopy (AES). The decomposition of methanol occurs readily on submonolayer Pt-modified C/W (110) surfaces. The presence of low-coverage Pt on C/W (110) effectively inhibits the undesirable pathway leading to production of CH4 on the unmodified C/W (110) surface. In addition, Pt-modified C/W (110) surfaces are active toward the dissociation of water. Furthermore, their surfaces display a relatively low desorption temperature for carbon monoxide at similar to 329 K. The results on the Pt-modified C/W (110) surfaces are also compared to our earlier studies on the Pt-modified C/W (111) and PVD (physical vapor deposition) synthesized WC surfaces. Overall, the comparison of Pt/C/W (110), Pt/C/W (111), and Pt/WC surfaces confirms a synergistic effect by supporting submonolayer Pt on tungsten carbides, leading to higher activity toward the dissociation of methanol and water and a weaker bonding of carbon monoxide. Such a synergistic effect should be advantageous for the potential application of Pt-modified carbides as fuel cell electrocatalysts. (c) 2005 The Electrochemical Society. [DOI: 10.1149/1.1938107] All rights reserved.