A spinel-type LiCrMnO4 compound was synthesized and its chemical and electrochemical lithium intercalation reactions were studied. The content of inserted lithium ions by chemical lithiation using n-butyllithium was ca. 1 mol per unit formula. The powder X-ray diffraction patterns of the intercalated product showed an apparent structural change. The crystal symmetry changed from cubic to tetragonal, accompanied by lithium intercalation. It was found from the Rietveld refinement of the intercalated product that this lowering in the symmetry occurs due to the Jahn-Teller effect of Mn3+ ions produced with intercalation.