A kinetic analysis was completed on supported Pt catalysts for the water-gas shift (WGS) reaction under typical fuel processing conditions. It was found that the turnover rate (TOR) of the WGS reaction at 300°C (6.8% CO, 22% H2O, 8.5% CO2, 37.3% H2, and balance Argon) was affected by the support and followed the order SiO2-Al2O3 (1 x 10-3 s-1) < Al2O3 (4 x 10-2 s-1) < SiO2 (8 x 10-2 s-1) < La2O3 ~ TiO2 ~ ZrO2 ~ CeO2 (3-7 x 10-1 s-1). Turnover rates reported in the literature for Pt supported on TiO2, ZrO2, and CeO2 agree with our reported values. While we do not fully exclude the fact that the support could be participating in the WGS reaction, our results show that there is no significant difference in the TORs at the conditions studied on Pt supported on La2O3, TiO2, ZrO2, or CeO2. If the supports were playing a vital role in the WGS mechanism, one would expect the rate to change due to the varying degree of reducibility of the supports. No particle size dependence was found for the TOR on Pt/Al2O3 in the range of particle size studied (1.5 to ~10 nm). The experimentally observed reaction orders for all the catalysts regardless of the support were ~ 0.1 for CO, ~ 1 for H2O, ~ 0 for CO2, and ~ 0.5 for H2. A single site Langmuir-Hinshelwood mechanism with decomposition of a carboxylate intermediate being the rate determining step can describe the experimentally observed reaction orders. The relative CO coverage under WGS conditions (6.8% CO, 11% H2O, 8.5% CO2, 37.3% H2, and balance Argon) was measured by DRIFTS and it followed the order ZrO2 (~98%) > Al2O3 (~92%) > CeO2 (~87%) > SiO2 (~85%) > TiO2 (~69%). These coverages as well as the normalized formate surface concentration did not track the changes in the TOR and no significant trends were observed in the measured reaction orders. Our results suggest that the formates are spectator species. At this time, we believe that alumina and silica have a deleterious effect on the rate.