Some advanced oxidation processes (AOP's) such as Fenton H2O2/Fe2+, photo assisted Fenton UV/H2O2/Fe2+, UV photolysis, and photo assisted Fenton like UV/O-2/Fe2+ have been tested for the degradation of Gemfibrozil in aqueous solution in a batch system and then in a membrane reactor. A nanofiltration/ reverse osmosis type cross-linked polyamide, UTC-60 ( Toray) membrane ( 19 cm 2) was used. In the batch degradation tests, the gemfibrozil, used at 5 mg/L, was degraded by employing the four AOP's but numerous peaks of intermediates were observed at the HPLC. Indeed DOC analyses showed poor mineralization in the case of photolysis (3.1%) and UV/O-2/Fe (10%), while it was 62% using the photo assisted Fenton and 24% using the Fenton. Thus in the membrane reactor only the Fenton and the photo assisted Fenton were tested. Obtained results showed a drug degradation higher than 92%, a mineralization higher than 55%, and a membrane retention of the catalyst in solution higher than 95%.