BACKGROUND: Palm oil mill effluent (POME) is a liquid waste that is highly polluting and has a significant impact on the environment if not dealt with properly. POME contains oil and carotenes that needs to be treated before discharge. In this work solvent extraction was used to recover oil-containing carotenes from POME. Optimum conditions for the extraction of oil and carotenes from POME were determined using response surface methodology. RESULTS: A central composite design was used to investigate the effects of three independent factors, namely solvent: POME ratio, mixing rate (rpm) and mixing time (min) on the responses, extracted oil and carotenes recovery. The optimal conditions for extraction of oil and carotenes from POME were 8:10 solvent: POME ratio; 500 rpm mixing rate and 25 min mixing time. Under these conditions, the amount of oil extracted from POME was 7885 mg L-1, and carotenes recovery was 87.1%. CONCLUSION: The experimental values agreed with those predicted, thus indicating the suitability of the model employed in optimizing the extraction parameters. A high yield of carotenes was obtained under the optimized conditions, with relatively low solvent levels. (C) 2009 Society of Chemical Industry