The production of palm oil mill effluent (POME) has caused serious environmental hazards. The most popular treatment for POME is biological treatment (anaerobic digestion method) by adopting the ponding system. Anaerobic sludge solids build-up in the ponding system has been accepted as a feature of anaerobic digestion of POME. While anaerobic digestion is widely accepted as a viable and cost-effective method. For the treatment of POME, anaerobic treatment alone has difficulty meeting the Department of Environment (DOE) Malaysia discharge limits due to the high organic content. Hence, subsequent post-treatment such as advanced oxidation process treatment is vital to meet the discharge limits. The current study evaluated the effectiveness of the combined oxidation method by using heat and transition metal (iron oxide) to activate persulphate as a post-treatment of biologically treated palm oil mill effluent (BIOPOME). The performance was assessed by measuring the efficiency in terms of the removal of chemical oxygen demand (COD) and colour. The maximum removal efficiency per litre of BIOTPOME was 64 - 69% (COD) and 88 - 93% (Colour) at a temperature of 60 C, pH 9, dosage of 2.03 g iron II salt and 1.28 g persulfate. The process was effective to further make the wastewater amenable to discharge in the environment.