Optical and electrical properties of thin film p-Cu2 O/n-CuO junction were investigated. It was found that such junction can be fabricated by controlled oxidation of copper films in 400-500 o C in different O2 and Ar partial pressures. Clear diode characteristics were observed at room temperature (25 o C) for the thin film device fabricated on transparent conductive glass substrates. The breakdown voltage and threshold voltages were -0.95 V and 0.75 V, respectively. Optical properties of Cu 2 O and CuO thin films clearly indicated that each film and their junction well agree with previously reported data.