The need for energy is increasing while fossil fuels are depleting. Utilization of oil palm waste and plastic waste are alternative ways to get renewable energy. The purpose of this study was to determine the characteristics of the heating temperature increase to reach the temperature of 105 ° C. This study contains a mixture of waste biomass and plastic waste, namely oil palm empty bunch waste and plastic bottle waste (PET) with microwave heating of 800 Watt power has been carried out. The addition of an absorber to increase the absorption of microwaves is done using coconut shell charcoal. The reduced composition of empty bunches and PET are 100: 0, 75:25, 50:50, 25:75 and 0: 100. a data logger and hyper terminal are used to record temperature and mass data automatically per second. The result showed that the heating rate is 1,859 ° C / s, 1,311 ° C / s, 0,975 ° C / s, 0,736 ° C / s, 0,328 ° C / s, while the flow rate mass was 0.0534 g / s, 0.0325 g / s, 0,0217 g / s 0,0129 g / s, 0.00594 g / s and energy consumptions is 32000 J, 43200 J, 61600 J, 79200J, 171200 J. From the above data it can be seen that showing PET into the biomass mixture and PET will add value to increase and accelerate mass flow for energy consumption will increase.