Au and/or Ni nanoparticles were synthesized by radiolysis on TiO2 (commercial P25) at various composition (metal content). The modified photocatalysts were characterized by High Resolution Transmission Microscopy (HRTEM), Energy-Dispersive X-ray Spectroscopy (EDS), UV–vis Diffuse Reflectance Spectroscopy (DRS) and X-ray Photoelectron Spectroscopy (XPS). The charge-carrier mobility was studied by Time Resolved Microwave Conductivity (TRMC). The photocatalytic activities were tested under UV–vis irradiation using polychromatic and monochromatic light (action spectrum analysis of apparent quantum efficiency). Surface modified TiO2 with Au and Ni nanoparticles showed high photocatalytic activity for hydrogen evolution from aqueous methanol solution. The enhanced hydrogen evolution rate was obtained for TiO2 co-modified with Au and Ni, where synergetic effect of the two metals was revealed. A very small amount of gold associated to nickel (atomic ratio Ni:Au 5:1 with a total optimized metal loading of 0.5 at%) can induce a significant increase in H2 formation.