A cathode material for use in a lithium secondary battery of excellent thermal stability contributing to the improvement of safety of the battery and having large discharging capacity, as well as a method of manufacturing the cathode material for use in the lithium secondary battery, based on the improved method for measuring the thermal stability of the cathode material, the cathode material comprising a compound represented by the chemical formula: Li.sub.xNi.sub.yCo.sub.zM.sub.mO.sub.2 in which the material is powdery and the BET specific surface area is 0.8 m.sup.2/g or less, M in the chemical formula represents one or more of element selected from Ba, Sr and B, and x, y, z and m are, respectively, 0.9.ltoreq.x.ltoreq.1.1, 0.5.ltoreq.y.ltoreq.0.95, 0.05.ltoreq.z.ltoreq.0.5 and 0.0005.ltoreq.m.ltoreq.0.02.