Heat generation occurs in landfills due to the degradation of organic matter. This paper aims to evaluate the heat generated due to the organic matter degradation of synthetic municipal solid waste using a bioreactor. A double-layered bioreactor is developed for the waste degradation test, during which the waste temperature, ambient temperature, gas emissions and total degraded organic matter are measured. The waste degradation tests last more than 350 h and indicate peak values for both the waste temperature and the rate of gas emission. The heat generated from waste degradation is determined by accounting for increases in the waste temperature, gas emissions and bioreactor conduction. The total heat generated per unit mass of the dry organic matter ranges from 1503 to 1776 kJ, which shows reasonable comparison results with the reported heat values. The variation in the total heat generated with waste degradation time is well predicted by an empirical formula, in which the heat parameters are correlated with the times of the peak waste temperature and peak heat generation rate.