Effect of crystalline structure, anatase and rutile, on the production of OH center dot and O-2(center dot-) by TiO2 photocatalytic reaction was investigated. The OH center dot radical free from the TiO2 surface was monitored by the fluorescence intensity of 2-hydroxyl terephthalic acid produced by the reaction with terephthalic acid. Superoxide radical was detected by the chemiluminescence probe method with luminol. Formation rate of OH center dot with rutile photocatalysts was significantly lower than that with anatase photocatalysts. By the addition of H2O2, the formation rate of OH center dot was significantly increased for rutile and for anatase mixed with rutile by 10-20%, while pure anatase showed an opposite tendency. We suggest that the adsorption structure of H2O2 on the rutile TiO2 surface is preferable to produce OH center dot. In photocatalytic production of O-2(center dot-), rutile surpassed anatase in stabilizing the produced O-2(center dot-). On H2O2 addition, anatase surpassed rutile in the photocatalytic activity to produce O-2(center dot-) from H2O2. (C) 2007 Elsevier B.V. All rights reserved.