New method of improving photocatalytic activity of commercial TiO2 (Degussa P25, Germany) is presented. Modified P25 has better photocatalyfic activity and "practical efficiency" than unmodified TiO2 Degussa P25. The modification of P25 was conducted under elevated pressure in organic solvent atmosphere. It leads to built in carbon into TiO2 structure without surface hydroxyl groups reduction. The photocatalytic activity of modified P25 was tested during three azo dyes (reactive red, reactive black, direct green - Boruta-Kolor Company, Poland) decomposition under UV light irradiation. The photocatalytic activity of modified P25 was two times higher than for unmodified P25. Moreover after the process the new photocatalyst had better sedimentation and filtration was easier. (c) 2007 Elsevier B. V. All rights reserved.