A cathode active material and non-aqueous electrolyte secondary battery. The non-aqueous electrolyte secondary battery includes a positive electrode and a negative electrode which are electrochemically doped and dedoped with lithium; and an electrolyte disposed between the positive electrode and the negative electrode. The positive electrode contains a cathode active material including a mixture of: a first cathode active material represented by a general formula: Li.sub.tCoM.sub.sO.sub.2 where M represents a metal, 0.ltoreq.s.ltoreq.0.03, and 0.05.ltoreq.t.ltoreq.1.15; and a second cathode active material represented by a general formula: Li.sub.xNi.sub.(1-y-z)Co.sub.yMn.sub.zA.sub.aO.sub.2 where A represents a metal, 0.05.ltoreq.x.ltoreq.1.15, 0.15.ltoreq.y+z.ltoreq.0.70, 0.05.ltoreq.z.ltoreq.0.40, and 0.ltoreq.a.ltoreq.0.10.