The support effect on the low-temperature propane combustion over platinum catalysts was investigated by kinetic study. The catalytic activity of supported platinum catalysts varied with the support material, and Pt/SiO2-Al2O3 showed much higher activity than Pt/ZrO2, as already reported. The reaction order for oxygen was negative and that for propane was positive. The reaction order for propane and oxygen also greatly depended on the support material: Pt/ZrO2 gave anomalous reaction orders, i.e., -2.9 for oxygen and 3.4 for propane. Further, oxidized Pt/ZrO2 showed a Long-term change of the catalytic activity with time-on-stream, compared with oxidized Pt/SiO2-Al2O3 From these results, it was concluded that high catalytic activity of platinum on acidic support is attributed to high ability to maintain the metallic state of platinum with high oxidation-resistance and high reducibility of platinum oxide.