Anaerobic digestion of oil palm empty fruit bunches (EFB) is considered an effective method for non-renewable energy substitution through biogas production. However, lignocellulosic recalcitrance structure of EFB is one of the main difficulties in achieving high biogas production for anaerobic co-digestion with palm oil mill effluents (POME). In this study, EFB was pre-treated with subcritical water (SCW) at low (120°C) and high (180°C) temperatures for 10 to 30 min to enhance biogas production. The characteristics of EFB after SCW pre-treatment were evaluated to identify changes in physicochemical characteristics. The combination pretreatment of 180°C for 10 min with 546.18 mL g-1 volatile solid (VS) biogas yield and 421.41 mL CH4 g-1 VS methane yield revealed the highest biogas production. Meanwhile, co-digestion of SCW pre-treated EFB with POME led to a removal of more than 66% VS. The sugars released were analysed in liquid fraction of SCW pre-treated EFB where glucose, xylose, cellobiose, mannose and galactose were detected. Notably, kinetic study of biogas production of pre-treated EFB using modified Gompertz model revealed that pre-treatment improved the lag phase, and the highest biogas production rate was observed at 19.80 mL g-1 VS. day. In conclusion, co-digestion of EFB with POME for methane production can be improved with the use of SCW pre-treatment.