Kinetic studies for the water-gas shift (WGS) reaction under fuel reformer conditions for fuel cell applications (6.8% CO, 8.5% CO₂, 22% H₂O, 37.3% H₂, and 25.4% Ar) were performed on Pt catalysts. For Pt on alumina, the power rate law is r_WGS= k [H2O]^0.9 [CO2]⁰ [CO]^0.1 [H2]^-0.6 with an apparent activation energy of 84 kJ/mol. The negative apparent reaction order indicates inhibition of the forward rate by H2. When titania and ceria were used as a support, the turnover rate for WGS was 12 and 50 times that on alumina supported Pt catalysts, respectively. The corresponding apparent activation energies and power law rates for titania and ceria supported Pt are 55kJ/mol, r_WGS= k [H2O]^0.8 [CO2]⁰ [CO]^0.2 [H2]^-0.7, 78 kJ/mol and r_WGS= k [H2O]^0.9 [CO2]⁰ [CO]^-0.05 [H2]^-0.5, respectively. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) confirmed that the Pt surface is 90% saturated with CO under reaction conditions for the Pt/alumina catalysts. For the Pt/titania catalyst the CO coverage was dramatically reduced to 30%. The decrease in CO coverage in the Pt/titania catalyst is accompanied by an increase in the CO apparent reaction order. A sequence of elementary steps was proposed to explain the observed reaction kinetics on Pt and to qualitatively predict the changes in CO coverage observed with DRIFTS. All the Pt/alumina, Pt/titania and Pt/silica catalysts tested presented a compensation effect between the apparent activation energy and the apparent pre-exponential factor. Potential reasons for this observation will be presented.