LiMn1.5−x M2x Ni0.5−x O4 (M=Co or Cr, 0.0≤ x ≤0.2) compounds were synthesized by the sol–gel method. It is found from X-ray diffraction analysis that single spinel phases are obtained for both Cr3+- and Co3+-substitution, but a small cation mixing between the 8a and 16d sites is found only in the Co3+-substitution case. All of the compounds exhibit M–T curves characteristic of ferromagnetic materials. As the substitution degree is raised, the saturation magnetization at 4.2K decreases and the Curie temperature shifts lower, irrespective of the kind of the substituent. That is, the cation substitution yields a reduction of the ferromagnetism. Additionally, both Cr3+- and Co3+-substitution have a large influence on the electrochemical properties. The Cr3+-substitution induces a rise in the average operating potential without a loss of redox capacity, while both the average operating potential and the redox capacity decrease with an increase in the Co3+-substitution degree.