LaFe x Ni 1-x O 3+σ oxides (0≤x≤1) were prepared by the decomposition of amorphous citrate precursors. X-ray diffraction patterns revealed perovskite structure with a rhombohedral distortion for substitution x 2 and balance nitrogen. The intrinsic activity was higher for LaNiO 3 than for LaFeO 3 , and this was explained on the basis of the higher capability of Ni 3+ ions to adsorb oxygen. However, even higher activity was observed on the Fe 3+ substitution by Ni 3+ with two clear maxima at x=0.10 and x=0.50. This activity pattern was related to the mixed valence states Ni(III)+Fe(IV) generated by the LaFe x Ni 1-x O 3 solid solution, which enhances the bonding of oxygen on the surface.