This study was an investigation into the effect of a number of operating parameters on the photoelectrocatalysis removal of Reactive Red 120 (RR 120) and Acid Orange 2 (AO 2) from aqueous solutions. Ni-TiO2 was used as the photocatalyst, which was applied in suspension to the solutions to achieve a larger catalyst surface area. Photocatalyst dose, dye concentration, pH, bias potential, and electrolyte concentration were found to be optimum at 0.6 mg L-1, 50 mg L-1, 7, 1.6 V, and 5 mg L-1, respectively. Substantial reduction was observed in the COD values of the solutions, suggesting that the treatment was effective. Photocatalyst efficiency was evaluated using FT-IR, SEM, TEM, XRD, EDX, and BET techniques. Intermediate compounds were revealed during GC-MS analysis for the characterization of post-treatment products. Pathways were proposed for the removal of the dyes. Solar cells supplied the energy required by the experiment, making it unnecessary to purchase electricity. Cost analysis was also performed for the treatment process. (C) 2013 Elsevier B.V. All rights reserved.