The photoelectrochemical properties of the copper oxide thin film coated on the n-type silicon electrode were investigated as a function of film deposition temperature. The variation in the deposition temperature affected the film morphology and the ratio of copper to oxygen. Ln case of the films deposited below 200 degrees C, the main phase was found to be CuO while the amount of the Cu2O phase increased with further increases in deposition temperature. The n-silicon photoelectrode showed enhanced photocurrent-potential (I-V) properties by forming a copper oxide/n-silicon heterojunction. Ln particular, the electrode, which mainly consisted of a CuO phase, showed better photoelectrochemical conversion efficiencies compared to the Cu2O phase. This result was explained in terms of the electrical conductance and transmittance of the copper oxide film.