Ti oxide films with thicknesses in the 1.9-8.0 μm range were sputter deposited onto electrically conductive transparent glass substrates X-ray diffraction indicated a dominating rutile structure. The films were used to investigate photo-electrocatalytic degradation of 4-chlorophenol in water-solution, employing a specially designed reactor. UV light was used for the photocatalysis, and a bias potential was applied for avoiding electron-hole recombination. The photocurrent and the kinetics of the catalytic reaction were tested with potentiostatic and spectrophotometric measurements. The reaction products were investigated using different arrangement of a Ti oxide working electrode and a Pt counter electrode. UV irradiation through the glass substrate yielded an enhancement of the reaction kinetics for increased film thicknesses and applied bias potential.