The biodegradation of sunflower oil in wastewater containing saccharose is studied using an activated sludge technique and an aeration tank provided with a baffle in order to increase oil and fat residence time. Concentration levels of mixed liquor suspended solids (MLSS) ranged from 0.5 to 1.8kgCOD/kgSSLM/day and intake concentration of oils and fats ranged from 191,6 to 937,5mg.l(-1). An estimate of the biodegraded material was obtained by means of a mass balance. The results show degradation levels ranging from 74 to 44% with removal efficiencies of 93 to 86%. This process performance includes the removal due to flotation. In the other hand, it is observed that the oil biodegradation levels decrease as the intake oil concentration increases. At the effluent, growth of the filamentous mass is observed and, consequently, an increase of the sludge volume index is registered, reaching figures of up to 300mg.l(-1), way over the recommended standard (150mg.l(-1)). Finally it is worth mentioning that the observed COD biodegradation ranges from 87 to 48% and the removal from 95 to 90%. These results are higher than those typically observed for oil and fat, a result that can be explained by the presence of saccharose.