Cobalt Oxide/ Zinc Oxide nanocomposite was synthesized by dropwise addition ofCo(NO)3.6H2O and Zn(NO3)2.4H2O solutions to KOH solution at different temperatures followed bycalcination at 300oC for 4 h. The morphology and structure of nanoparticles and the influence oftemperature on particle size were studied using scanning electron microscopy (SEM) and X-RayDiffraction (XRD). Minimum particle size was obtained before calcination at 70oC. In addition, thespherical, semispherical and flake-shaped nanoparticles were observed at ambient temperature. Onthe other hand, Co(OH)2 was transformed to Co3O4, ZnO flakes were eliminated, and particle sizechanged during calcination. Synthesized samples at 50oC and 70oC showed an increase size aftercalcinations; however, elimination of flakes during calcination caused particle size reduction forsynthesized sample at ambient temperature.