This paper presented a theoretical framework for precise determination of the isosteric heat of adsorption for non-ideal gases. The derived equation had been applied for various adsorbent-refrigerant pairs. Highly porous activated carbon powder, namely Maxsorb III and activated carbon fiber of type (A-20) were used as adsorbents with HFC-134a and HFC-410a as refrigerants. The isosteric heat of adsorption data showed lower values comparing to the isosteric heat of adsorption without the consideration of non-ideality of gases. An empirical formula to perceive the isosteric heat of adsorption of HFCs gases on to activated carbons had been extracted. Effect of the proposed isosteric heat of adsorption on the performance of adsorption cooling system based on activated carbon powder/HFC-134a had also been discussed in detail. (C) 2015 Elsevier Ltd. All rights reserved.