With the help of an experimental data base, the overall heat transfer coefficient of the double function heat exchanger (condenser/evaporator) of a novel adsorptive solar ice maker (ASIM) was estimated. The calculation shows that this parameter, which is required for simulation, is not constant during the adsorption–evaporation phase and that it is higher during the water freezing phase. With the help of a predictive mathematical model the operation of the studied ASIM was simulated and the results were analysed. They showed that with a consistent design of the different components of this machine the daily ice production could exceed 5.2kg, with a COPs of more than 0.14. This value of the COPs is very interesting in comparison with those usually obtained from the ASIMs operating with separate condenser and evaporator, i.e. 0.08–0.2, according to the meteorological conditions or technologies.