Three reagent dosing strategies used in the solar photo-assisted decolorization of a mixture of sulfonated dyes consisting of acid blue 113, acid orange 7 and acid red 151 were evaluated. Results demonstrated that the dosing strategy influenced both reagent consumption and the biodegradability and toxicity of the effluent. In one strategy (E-1), the Fenton's reactants were dosed in a punctual mode, while in the other two strategies (E-2 an E-3), the reactants were dosed continuously. In the E-2 strategy the reactants were dosed by varying the duration of the injection time. In the E-3 strategy, the reactants were dosed during 60 min at a constant rate, but with different concentrations. All cases showed that feeding the reactor between 40% and 60% of the maximal dose was sufficient to decolorize more than 90% of the mixture of azo dyes. The E-1 strategy was less effective for aromatic content reduction. Conversely, the continuous addition of the reagents (E-2 and E-3 strategies) improved the aromatic content removal. E-3 strategy was substantially more appropriate than E-1 strategy due to improved the effluent quality in two key areas: toxicity and biodegradability. (C) 2012 Elsevier B.V. All rights reserved.