Pt and Pt-Sn catalysts supported on alumina and niobia were prepared to investigate the geometric and ligand effects by thermal desorption and infrared of CO adsorption, as well as by studying their catalytic activity and selectivity for 1,3-butadiene hydrogenation. Results have shown a significant increase in the platinum electronic density on Pt/Nb2O5 catalysts caused by the SMSI effect. Pt-Sn/Nb2O5 catalysts have shown alteration of electronic density after reduction at higher temperatures due to alloying of Pt-Sn on niobia surface. Results obtained in the metallic phase for the alumina supported catalysts could be successfully explained by ensemble effect. Both niobia and alumina surfaces seem to participate in CO adsorption/desorption process through formate species and carbon monoxide plus hydroxyl reactions.