Copper oxide thin films are deposited using an ultrasonic-assisted spray pyrolysis deposition (SPD) system. To investigate the effect of substrate temperature and incorporation of a chelating agent on the growth of copper oxide thin films, the structural and optical properites of the copper oxide thin films are analyzed by X-ray diffraction (XRD), field-emssion scanning electron microscopy (FE-SEM), and UV-Vis spectrophotometry. At a temperature of less than 350 °C, threedimensional structures consisting of cube-shaped Cu2O are formed, while spherical small particles of the CuO phase are formed at a temperature higher than 400 °C due to a Volmer-Weber growth mode on the silicon substrate. As a chelating agent was added to the source solutions, two-dimensional Cu2O thin films are preferentially deposited at a temperature less than 300 °C, and the CuO thin film is formed even at a temperature less than 350 °C. Therefore the structure and crystalline phase of the copper oxide is shown to be controllable.