Nanoparticles of metal and metallic oxides have become a very active research area in the field of material chemistry. The surface effect is mainly responsible for deviation of the properties of nano-materials from that of the bulk. Nanosize copper oxide was synthesized by hydrolysis of copper salts in basic medium using biodegradable non-ionic polymer polyethylene glycol (PEG) as surface active agent The X-ray powder diffraction patterns (XRD) present typical peaks of copper oxides formed. The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images determined the shape and the nanosizes of the particles of about 10-30nm. The results exhibited the role of intermediate nanosize copper hydroxide species on the formation of copper oxide nanoparticles. The influence of synthesis temperature, reaction time, calcination temperature, etc. was studied.