We look at the operation of compression/absorption cycle machines in order to produce a high-temperature heat pump. The useful effect of the machine lies in the absorber during absorption of vapour with a high refrigerant content by the solution with a low refrigerant content. We create a thermodynamic model of falling film absorber, which includes a difference at equilibrium. This model involves a mass transfer at the interface, and a heat transfer in the film. Based on this model, we create a global model (with analytical integration) of the transfer equations, a local model (with numerical integration) and an intermediate model. The local model can be used for accurate plotting of the operating curve (the operating curve represents the changing thermodynamic state at the heart of the film). It also enables the calculation assumptions of the global model to be validated, or not. Finally, we perform a parametric study of the local model, which gives more exact information on the operation of the absorber. (author). 3 refs., 12 figs., 3 tabs.