The dynamic reduction behavior of a highly dispersed Pt4+ to Pt-0 particles on TiO2 and Al2O3 surfaces under the reductive atmosphere with an in situ time-resolved energy-dispersive X-ray absorption fine structure (DXAFS) analysis. A highly dispersed Pt4+ on TiO2 was reduced to Pt-0 even at room temperature. In contrast, a highly dispersed Pt4+ on Al2O3 was gradually reduced to Pt-0 even at 473 K. This result may suggest that the semi-conductive behavior of TiO2 promotes the low temperature adsorption of hydrogen and supply of hydrogen atom to Pt4+ to be reduced and the activation of hydrogen on Al2O3 requires high temperature.