Provided are a cathode active material for a non-aqueous electrolyte lithium secondary battery, a process for preparing the same and a lithium secondary battery comprising the same. The cathode active material for a non-aqueous electrolyte lithium secondary battery is represented by the formula Li.sub.aNi.sub.1-(v+w+x+y+z)Mn.sub.vCo.sub.wM.sub.xM'.sub.yM''.su- b.zO.sub.2 wherein M, M' and M'' are independently selected from the group consisting of Al, Mg, Sr, Ca, P, Pb, Y and Zr, and mixtures thereof, a is in a range of 0.9 to 1.05, 1-(v+w+x+y+z) is in a range of 0.685 to 0.745, v is in a range of 0.05 to 0.06, w is in a range of 0.20 to 0.24, and x+y+z is in a range of 0.005 to 0.015.