This paper presents the results obtained in the degradation of ibuprofen by ozonation. This study aims to evaluate the degradation of ibuprofen by ozonation once the operating variables have been optimized, investigating the degradation and degradation efficiency of the compound and assessing the toxic effect of ibuprofen and of the intermediate compounds generated during oxidative treatment. Work was carried out to optimize the four operating variables: pH, conductivity, hydraulic retention time and the use of a maze of pipes to enhance contact between the ozone and the drug. All the trials were conducted in a purpose-built pilot-scale reactor. Analyses of the compound were carried out after solid-liquid phase extraction on high resolution liquid chromatography (HPLC). Working under optimal operating conditions (pH=9, HRT=20min and 12+/-2gN/m 3 ), a degradation value of 99% was obtained, although degradation efficiency or mineralization of the compound was not achieved. The toxicity of ibuprofen and its intermediate compounds formed during the oxidative process was likewise studied. This toxicity was found to increase with increasing initial concentrations of the compound, with the intermediate compounds thus formed being more toxic than the starting compound.