Hydroxyapatite/TiO2 compound had been successfully synthesized by hydrothermal treatment of HAp powders and Ti(OH)(4) solutions at 100-190 degrees C with different hydroxyapatite/TiO2 proportion. The hydroxyapatite/TiO2 compounds were characterized by various methods including FT-IR, BET, TEM, EDX, XRD and ICP. TEM observation showed that small granule TiO2, identified as anatase crystals of 3-5 nm, were deposited on HAp rod-like crystals. X-ray diffraction results indicated that hydroxyapatite and anatase phase appeared and with higher colloidal TiO2 added into the HAp/TiO2 compound, there was more anatase appeared. With increasing colloidal TiO2 addition, FT-IR spectroscopy revealed PO43- band at 572, 602, 962, 1046, 1090 cm(-1) became decreasingly, and ICP spectrometry revealed the content of Ti4+ increased. The photocatalytic activity of the hydroxyapatite/TiO2 particles was examined by decomposition of methylene blue (MB). The results showed that photocatalytic properties of hydroxyapatite/TiO2 compound are more effective than that of hydroxyapatite and TiO2. (c) 2005 Elsevier B.V. All rights reserved.