The present study was focused on the degradation of Atrazine (ATZ) and major by-products (DEA, DIA, DEDIA and ATZ-OH) from water by photoelectrocatalytic (PEC) oxidation process under solar light. The undoped TiO2, sub-stoichiometric TiO2 (TiO2-x) and codoped TiO2 (TiO2:WN) photoanodes were prepared by means of a radio frequency magnetron sputtering (RF-MS) deposition process. The X-ray photoelectron spectra (XPS) analysis shows that the N and W atoms were incorporated into the O and Ti lattice sites of TiO2 respectively (case of TiO2:WN film), while the XPS measurements of the TiO2-x films composition was determined to be TiO1.9. The UV-Vis transmittance spectra shows that in the case of the TiO2:WN films, the presence of nitrogen and tungsten improve the optical response of TiO2 under visible range compare to the presence of oxygen vacancies in to the TiO2-x films. The experimental results under solar light with an initial concentration of ATZ (100 mu g L-1) show that after 180min of treatment, the degradation of ATZ were 34.98%, 68.57% and 94.33% using TiO2, TiO2-x and TiO2:WN photoanodes, respectively. These results of ATZ degradation proved that TiO2:WN photoanode was more photoactive under solar light. The evolution by-products of ATZ under sunlight show that the principal mechanism of ATZ degradation was the oxidation of alkyl side chain and dealkylation. [GRAPHICS] .