The oxidative reforming of diesel over Co/La2O3 and Ru-Co/L2O3 catalysts derived from LaCoO3 perovskite precursors was studied. Physicochemical characterization by XPS, TPR and XRD revealed that the incorporation of Ru to LaCoO3 produces changes in LaCoO3 evidenced by a smaller size of the LaCoO3 particles and cobalt segregation on the LaCoO3 surface. The modifications in the structure of LaCoO3 induced by the addition of Ru directly affect the dispersion and morphology of Co particles developed under the reaction. The active phases derived from pretreatment of perovskites evolve differently with time on stream, being observed that the presence of a greater proportion of perovskite phase in the Ru/LaCoO3 sample produces an increase in catalyst stability. TPD-MS analysis also indicates that bulk oxygen release from the Ru-Co/La2O3 sample could improve its catalytic behaviour. The characterization of used samples reveals that improvements in the cobalt surface concentration and Co-La2O3 interactions contribute to the better catalytic stability of the Ru-Co/La2O3-derived catalyst. (c) 2007 Elsevier B.V. All rights reserved.