Abstract A new dynamic simulation program for predicting the transient behavior of absorption chillers with arbitrary cycle configurations has been developed. This program combines an object-oriented formulation and a parallel processing program architecture. A new algorithm for calculating the flow rate in a solution circulation line has been also developed. The simulated results of transient behavior of a double-effect absorption chiller cycle agree with the measured behavior of a machine from startup to shutdown. For example, predicted values of the cooling capacity of the chiller, the pressure and temperature of the high temperature generator agree with experimental values almost within 10%. This program has been applied in the development stage of a new machine: a high-performance triple-effect absorption chiller. As a result, this machine operates smoothly without any significant problems, and achieves COP of over 1.6 on the basis of high heat value.