TiO2 nanoparticles (C-TNT) with high visible light activity were obtained by carbonization of titania nanotubes (TNT) in an ethanol atmosphere under elevated pressure at 180 and 220 A degrees C. New material was characterised by means of UV-Vis/DR, FTIR/DRS, TEM, and XRD. The photocatalytic activity was tested during monoazo dye decomposition under artificial solar light irradiation. Modified photocatalyst (220 A degrees C, 4 h) had higher photocatalytic activity than both the pristine and commercial P25 catalysts.