Li, Co and Ni mixed oxides of composition LiNixCo2-xO4 (x = 0.25, 0.5, 0.75 and 1) were prepared at 280 degrees C by the Pechini sol-gel method. The Rietveld refinement of the X-ray diffraction data indicated that all the obtained compounds crystallize in the Fd3m space group characteristic of cubic spinel-related oxides. XPS studies on these oxides reveal the presence of Ni2+, Ni3+, Co3+ and Co4+ ions at the surface. The diffusion coefficients of the Li+ ion in the oxide lattice, determined by EIS measurements, are larger (10(-13) cm(2)s(-1) <= D <= 10(-10) cm(2)s(-1)) than that shown by the non-substituted cobalt-lithium oxide, LiCo2O4 (D = 10(-16) cm(2)s(-1)) and present similar values to those of layered oxides of related composition. (C) 2011 Elsevier B.V. All rights reserved.