There are currently 4.3 million hectares of oil palm plantation land in Malaysia and palm oil products export revenue was projected to exceed RM50 billions this year from last year's record of RM45.6 billions. With more than 500 palm oil mills, annually its produce some 13.9 million tonnes of crude palm oil and generate around 35 x 106 m3 palm oil mill effluent (POME) with pollution-load of 50,000 mg COD/L. POME is difficult to biodegrade because it contains high concentration of tryacylglycerols and degradative products, such as di-and monoacylglycerols and fatty acids. The objective of this study was to observe the performance of a hybrid membrane bioreactor (MBR) for POME treatment and to study the fouling mechanisms of membrane modules. Raw POME with organic loading of 1.8 kgCOD/m3.d was introduced into sequencing processes of anaerobic, anoxic and aerobic MBR in order to achieve biological nutrient removal. For the concentration of mixed liquor suspended solid (MLSS) was maintain at 8000 mg/L and the critical flux can be observed that transmembrane pressure (TMP) and fouling rate increased significantly. The critical flux was in the range of 14-16 LMH and fouling rate of 4-8 mbar/min. Membrane fouling due to cake resistance was 74% of total resistance in the zone of sub-critical, increased about 15% in the critical zone and rose to 96% in the supra-critical zone. The COD and SS removal were an average of 94% and 98% respectively.