An absorber is a major component in absorption refrigeration systems and its performance greatly affects the overall system performance. In this study, experimental analyses of the characteristics of heat transfer for removal of absorption heat in an ammonia-water bubble mode absorber were performed. The heat transfer coefficient was estimated as a function of the input gas flow rate, solution flow rate, temperature, concentration, absorber diameter and height, and input flow direction. The increase of gas and solution flow rate affects positively in heat transfer. However, the increase of solution temperature and concentration affects negatively. Moreover, under the same Reynolds number, countercurrent flow is superior to cocurrent flow in heat transfer performance. In addition, from these experimental data, empirical correlations that can explain easily the characteristics of heat transfer are derived.