Photoelectrochemical properties of titanium dioxide films in the anatase and rutile form which were prepared by the sol-gel method were investigated. The effects of oxygen defects on photoelectrochemical properties were investigated by varying the reduction conditions such as atmosphere, temperature, and time. It is shown that (i) oxygen defects play a key role in photocurrent characteristics, (ii) oxygen defects drastically affect electroluminescence characteristics, and (iii) the electrolumineseence intensity GAMMA(x), infrared band, which peaked at 840 nm, is indicative of the degree of reduction.