A cathode active material of formula (1) below, and a lithium secondary battery using the same, have an extended cycle life and effective charging/discharging characteristics and include a compound of formula (1) below: Li.sub.xCo.sub.yM.sub.1-yA.sub.2 (1) where 0.95.ltoreq.x.ltoreq.1.0; 0.ltoreq.y.ltoreq.1; M is at least one selected from the group consisting of Ni, Fe, Pb, Mg, Al, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Mn, and Cr; and A is one selected from the group consisting of O, F, S, and P. The cathode active material has, as measured by Raman spectroscopy, a ratio of peak intensities between spinel and hexagonal A.sub.1g vibrational modes in an approximate range of 1:0.1-1:0.4, a ratio of peak intensities between hexagonal A.sub.1g and E.sub.g vibrational modes in an approximate range of 1:0.9-1:3.5, and a ratio of peak intensities between spinel A.sub.1g and F.sub.2g vibrational modes in an approximate range of 1:0.2-1:0.4.