Nickel substituted lithium–cobalt oxides, LiCo1−x Ni x O2 (0<x<0.4), have been synthesized in a very short time by a solution combustion method at 350°C using diformyl hydrazine as a fuel. Pure phases with hexagonal lattice structure have been obtained. These compounds facilitate reversible insertion/extraction of Li+ ions with good discharge capacity between 3.0 and 4.4V versus Li/Li+. Results of the studies by powder X-ray diffraction, scanning electron microscopy, cyclic voltammetry, galvanostatic charge–discharge cycling and ac impedance measurements are presented.