LaCo1-xRuxO3 perovskites with different substitutions of Co by Ru (x = 0.01-0.1) have been investigated as precursors of catalysts for the oxidative reforming of diesel for hydrogen production. The physicochemical characterization of LaCo1-xRuxO3 perovskites revealed modifications in their structure, crystalline size and surface area with the incorporation of ruthenium into the perovskite lattice. The modifications in the perovskites affect the structure and morphology of the catalysts obtained by reduction of perovskites prior the reaction. In the catalysts derived from ruthenium-containing perovskites it is observed a better reducibility, smaller particle size of La2O3 and Co-0 phases and better surface concentration of Ru-0 particles with the increase in the degree of Co substitution in the perovskite. The modifications in the characteristics of the catalysts induced by the Co substitution in perovskite directly affect their catalytic behaviour in the oxidative reforming of diesel. It is found that the greater Co-0 + Ru-0 exposition and the higher extension of the La2O2CO3 phase achieved in catalysts derived from perovskites with higher cobalt degree of substitution produces an increase in the activity and stability of the catalysts derived. (C) 2010 Elsevier B.V. All rights reserved.