In this paper, NiCo2O4 spinel oxide was synthesized by the oxidation of Ni-Co alloy. The variables that affect the formation of spinel oxide include the Ni-Co ratio in the alloy, the oxidation temperature and time. 350°C is the upper oxidation temperature limit. And longer oxidation time is helpful. Surface roughness analysis shows that with the formation of NiCo2O4, the surface shows rougher.