Electron transfer dynamics of meso-tetrakis(p-carboxyphenyl)porphyrin [TCPP] adsorbed on colloidal TiO2 and AuTiO2 nanoparticles have been investigated by time resolved absorption and fluorescence spectroscopy. Optical absorption studies reveal that the TCPP form complex with TiO2 and AuTiO2 nanoparticles. Excitation of TCPP adsorbed on the TiO2 nanoparticle surface leads to electron injection on the conduction band of TiO2. Electron injection has been confirmed by direct detection of cation radical of the adsorbed dye (TCPP.). The rate constant for the electron injection process is determined from both the singlet and triplet state respectively. The rate of electron injection for TCPP-AuTiO2 is much faster than TCPP-TiO2. The injected electrons are quickly transferred to Au and it escorts to ignore the back electron transfer (recombination) process. (C) 2010 Elsevier Inc. All rights reserved.