The catalytic activity of Nb2O5 and Nb2O5/Al2O3-supported metal catalysts was evaluated in the n-heptane conversion, CO hydrogenation and butadiene hydrogenation. After high temperature of reduction (HTR), the metal adsorption capacity decreases on all the samples, due to the reduction of Nb2O5 With subsequent blocking of metal atoms and bimetallic effect. It was also observed that the activity decay caused by metal-support interaction was remarkably inhibited on the bimetallics with respect to the monometallics by comparing reaction rates after HTR. Thus, the addition of Rh to Co, Cu to Pd and Sn to Pt on niobia catalysts significantly altered the product distribution in Fischer-Tropsch synthesis (FTS) and in the hydrogenation and dehydrogenation of hydrocarbons, respectively. In addition, an unusual bifunctional effect was obtained in Pt/Nb2O5/Al2O3 catalyst. (C) 2000 Elsevier Science B.V. All rights reserved.