Thin films deposition techniques have been described in the book especially chemical deposition methods. Copper oxide thin films deposition using chemical spray pyrolysis chemical bath and drop-chemical deposition techniques and characterization such as compositional by AES structural by XRD morphological by SEM electrical optical by UViR double beam spectrometer photo-electrochemical and current-voltage analyses have been described. Also CdS thin film of spray pyrolysis deposition and ZnO thin film of electrochemical deposition methods have been described shortly. The characterizations of the CuO-CdS heterojunction for rectification and the characterization of the Cu2O-ZnO heterojunction for rectification and solar cell application have been described.