Abstract The effect of H2 reduction treatments on H2 chemisorption, ethane hydrogenolysis, and CO hydrogenation over Nb2O5-supported and Nb2O5-modified Ru catalysts has been studied to elucidate the nature of the metal-oxide interaction, and the results are compared with those of a SiO2-supported Ru catalyst. The Ru/Nb2O5 and Nb2O5–Ru/SiO2 catalysts after high-temperature reduction at 500 °C showed a typical SMSI behavior, while a specific Ru–niobia interaction, which resulted in a higher ethane hydrogenolysis activity, was induced even after low-temperature reduction at 200 °C.