Microstructure of the films changes on varying film preparation conditions, particularly the annealing temperature. The surface morphology of deposited copper oxide films on glass substrate show grains of micrometric sizes. Each of these grains might correspond to an aggregate of copper oxide crystallites. Kinetic grain growth has been evaluated in copper oxide thin films by the calculation of its grain size at different temperatures. Optical band gap of the films, measured by employing a UV-VIS spectrophotometer, lies at 1.73 - 2.40 eV. Hence, the films of copper oxide obtained by this method may be exploited as cheap and efficient solar light absorber.