The present work focuses on the phase transformation mechanism of TiO2 nanoparticles in photocatalytic ceramics. TiO2 nanoparticles were mixed with fused quartz, glaze No.1, and glaze No.2 respectively and heat-treated. The phase transformation behavior of anatase TiO2 was analyzed by XRD. The results show that the phase transformation behavior of anatase TiO2 in photocatalytic ceramics is highly dependent on the glaze compositions rather than the crystal size effect, which is significantly different with TiO2 alone. The phase transformation from anatase to rutile always starts near the softening temperature and finishes below the sphere temperature of the glaze. The higher flux contents in glaze the lower phase transformation temperature. The significant retarding effects of silica and phosphate on the anatase-to-rutile phase transformation appear negligible when modified TiO2 are applied in glaze. The eutectic liquid is essential for the phase transformation behavior of anatase TiO2 in photocatalytic ceramics. (C) 2013 Elsevier Ltd. All rights reserved.