Increased need for alternative energy sources has instigated much interest in conversion of solar energy to other useful forms of energy. Semiconducting oxide thin films have potential applicability in photovoltaic conversion of solar energy to electrical energy and thermal energy collection or reflection. Pyrolytic thin films of Sn02-x and r. f. sputtered thin films of CoOx were prepared in this study and analyzed for electrical, optical,and structural characteristics. The experimental techniques used for this investigation were X-ray diffraction, visible and infrared spectrometry, electron spectroscopy for chemical analysis, scanning electron microscopy, heat treatment, and electrical resistivity measurement carried out at different temperatures. The information obtained from this investigation has shed new light on the cause for conductivity in SnO 20-Z. Chlorine impurity atoms were found ~o remain in the film due to incomplete pyrolytic decomposition. Of great interest was the finding that this chlorine was not affected by annealing of the films. Resistivity increases caused by annealing were shown to arise from film oxidation and interdiffusion of film with glass substrate. / Master of Science