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.