Pure and Ln(3+) modified TiO2 photocatalysts (Ln(3+) = Eu3+ or Sm3+ ions) synthesized by a sol gel method as well as commercially available P25 were applied for photocatalytic generation of useful hydrocarbons and hydrogen from acetic acid. Structure and surface properties of the photocatalysts were characterized by XRD, UV-vis/DR, FT-IR and N-2 adsorption desorption measurements. The main gaseous products of CH3COOH decomposition were CH4 and CO2. Trace amounts of C2H6 and H-2 were also detected in the reaction mixture. Moreover, it was observed that the quantities of all identified gases increased with elongation of irradiation time. The most active photocatalysts towards CH4 and H-2 generation were Ln(3+)/TiO2 containing 0.05 mol % of Sm and Eu, respectively. The results revealed that the Ln(3+) modification can improve the effectiveness of the photocatalysts compared to pure and commercially available TiO2 provided that a proper amount of modifying ions is used. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.