Effect of a crystalline phase of TiO2 is investigated in the photodeposition processes of Rh metal nanopartides on TiO2 photocatalysts having anatase and rutile phase by means of in situ time-resolved energy dispersive X-ray absorption fine structure spectroscopy (DXAFS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The important factor was neither its crystallite size nor its specific surface area, and was the crystalline phase. In situ time-resolved DXAFS analysis clarified that the Rh metal nanoparticles with a uniform size appear on both anatase and rutile phases of TiO2, whereas the appearance rate of Rh metal nanoparticles decreases with the photoirradiation time only on the rutile phase of TiO2. The TEM observation and XPS depth analysis revealed that the bare surface of photodeposited Rh metal nanoparticles on the rutile is exposed, although that on the anatase is partially covered with TiO2 due to strong metal-support interaction (SMSI) between Rh metal nanoparticle and TiO2 delta. Crown Copyright (c) 2013 Published by Elsevier B.V. All rights reserved.