Herein, we report a synthesis of mesoporous PdO-TiO2 nanocomposites at different PdO (0-3 wt%) through simple one-step sot-gel reactions. Pd2+ ions have been immobilized into TiO2 networks by cross-linking triblock copolymer (Plutonic F123) as the structure-directing agents to develop highly efficient PdO-TiO2 photocatalyst. The produced PdO-TiO2 gel were calcined at 400 degrees C for 4h to remove organic materials. TiO2 nanoparticles with an average diameter are 8-10 nm and PdO nanoparticles are well dispersed and exhibit diameters of about 10-40 nm based on the PdO content. Our prepared photocatalysts have been compared with Pd/Aeroxide TiO2-P25 by the determination of the initial rate of HCHO formation generated by the photooxidation of CH3OH in aqueous suspensions to calculate the corresponding photonic efficiencies. The newly prepared PdO-TiO2 nanocomposites showed a more effective and high efficient photocatalytic activities for CH3OH oxidation to HCHO similar to 4 and 2 times than TiO2-P25 and Pd/TiO2-P25 respectively. In the present work, the photocatalytic activities of the obtained PdO-TiO2 nanocomposites were significantly higher than those of previously reported. To the best of our knowledge, the measured photonic efficiency xi = 19.5% of mesosporous PdO-TiO2 nanocomposites is found to be among the highest xi-values reported up to now. (C) 2012 Elsevier B.V. All rights reserved.