Different characteristics of cupric oxide (CuO) thin films, deposited onto glass substrates by spin coating from solutions, can simply be enhanced by using a suitable annealing temperature. Morphological, optical and electrical properties, together with surface roughness, phase purity and crystallite size of the synthesized films, are all affected by annealing at temperatures in the range 300 – 500 ºC. The recommended temperature for the production of thin layer of monoclinic CuO with preferred characteristics is 500 °C. Annealing the CuO films at higher temperatures is not recommended. The results confirm that CuO films have narrow to medium band gap values, in the range 1.8-2.7 eV. Therefore, the CuO films unstable at higher temperatures.