Helaktyn red F5B reactive dye was decomposed by electro-chemical oxidation on Ti/TiO2(30%)-RuO2(70%) and carbon fibre anodes. Cyclic voltammograms recorded proved the higher effectiveness of the process carried out on the carbon fibre electrode. The highest dye conversion calculated as changes in COD (23%) and TOC (13%) was achieved on the Ti/TiO2-RuO2 anode at the potential of 0,9 and 0,8 V, respectively. Results of electrolysis were independent on the electrode material. However, the electrolysis time was several times shorter on the carbon fibre than on the Ti/TiO2- RuO2, especially at lower electrolysis potentials. An increase in an electrical charge passing through the electrolytic cell with the carbon fibre anode resulted in almost full discolouration of the dye solution and in an increase in the dye conversion calculated as a change in TOC.