[ $La_{0.5}Ce_{0.5}Co_{1-x}Cu_xO_{3-{alpha}}$ ](X=0, 0.1, 0.3, 0.5) perovskites were prepared by coprecipitation method at pH 7 or pH 11 and its catalytic activity of selective CO oxidation was investigated. The characteristics of these catalysts were analyzed by $N_2$ adsorption, X-ray diffraction(XRD), SEM, $O_2$-temperature programmed desorption(TPD). The pH value at a preparation step made effect on particle morphology. The smaller particle was obtained with a condition of pH 7. The better catalytic activity was observed using catalysts prepared at pH 7 than pH 11. The maximum CO conversion of 98% was observed over $La_{0.5}Ce_{0.5}Co_{0.7}Cu_{0.3}O_{3-{alpha}}$ at $320^{circ}C$. Below $200^{circ}C$, the most active catalyst was $La_{0.5}Ce_{0.5}Co_{0.9}Cu_{0.1}O_{3-{alpha}}$, of which conversion was 92% at $200^{circ}C$. By the substitution of Cu, the evolution of ${alpha}$-oxygen was remarkably enhanced regardless of pH value at preparation step according to $O_2$-TPD. Among the different ${alpha}$-oxygen species, the oxygen species evolved between $400^{circ}C$ and $500^{circ}C$, gave the better catalytic performance for selective CO oxidation including $La_{0.5}Ce_{0.5}CoO_3$ in which Cu was absent.