Experiments based on Vibrio fischeri, activated sludge and Pseudomonas putida have been employed to check variation in the biocompatibility of an aqueous solution of a commercial pesticide, along solar photo-oxidative process (TiO2 and Fenton reagent). Activated sludge-based experiments have demonstrated a complete detoxification of the solution, although important toxicity is still detected according to the more sensitive V. fischeri assays. In parallel, the biodegradability of organic matter is strongly enhanced, with BOD5/COD ratio above 0.8. Bioassays run with P. putida have given similar trends, remarking the convenience of using P. putida Culture as a reliable and reproducible method for assessing both toxicity and biodegradability, as a substitute to other more time consuming methods. (C) 2008 Elsevier B.V. All rights reserved.