Abstract The adsorption of CO and H2 on a SiO2-supported Au6Pt cluster [(AuPPh3)6Pt(PPh3)](NO3)2 (1) has been studied by means of FTIR, TPD, and EXAFS. CO adsorbed on 1/SiO2 to form a CO-adduct complex, which exhibited an IR band at ca. 1972 cm−1. The adsorbed CO was desorbed below 403 K, showing a peak maximum at 363 K in TPD. There was little change in the coordination number of Pt–Au in Pt L3-edge EXAFS upon CO adsorption, but the coordination number of Au–Au in Au L3-edge EXAFS slightly increased and the peak ascribed to Pt–(Au)–P in the Pt L3-edge EXAFS Fourier transform remarkably increased. The increase in the intensity of the Pt–(Au)–P peak was interpreted by the multiple scattering effect owing to the change of Pt–Au–P bond angle. The original EXAFS oscillations at both Pt and Au L3-edges were regenerated after evacuation of the CO-adsorbed sample for 2 h at 353 K, indicating the recovery of the original cluster structure. This is entirely different from the case of the cluster 1 in solution, where the cluster framework is fragmented by the CO adsorption-desorption process. The adsorption of H2 on 1/SiO2 was totally reversible at room temperature; it provided no contribution to the EXAFS oscillation.