TiO2 was electrodeposited into the pores of hard alumite (Al/Al2O3/TiO2) by alternative electrolysis in (NH4)(2)[TiO(C2O4)(2)] solution, where the alumite was prepared by anodic oxidation of aluminum in sulfuric acid (Al/Al2O3). When the electrolysis was carried out in an (NH4)(2)[TiO(C2O4)(2)] solution under ac bias for the Al/Al2O3, a cathodic current due to the reduction of H+ and/or H2O was observed at about -10 V in measurement of the Lissajous figure, leading to the deposition of TiO2. Consequently, the TiO2 was deposited during an increase in pH due to the electrochemical reduction reactions of H+ and/or H2O in the pores of the alumite. The deposited TiO2 was highly dispersed in the pores of the alumite. The prepared TiO2 in the pores (Al/Al2O3/TiO2) showed high photocatalytic activity for the decomposition of acetaldehyde compared to TiO, deposited directly on an aluminum surface (Al/TiO2).