The purpose of this paper is to provide empirical correlations for isosteric heats of adsorption on carbon based adsorbents for two refrigerants namely ethanol and HFC 134a. A non-dimensional correlation which partitions the contributions of the concentration and temperature dependence is proposed. The correlation is tested out against data obtained from experimental isotherms of ethanol adsorption on activated carbon fibers [ACF (A-20) and ACF (A-15)] and HFC 134a on two specimens of activated carbon powders and one specimen of carbon granules. It is expected that the suggested correlation will be useful for designers of adsorption chillers where indenting heat inventories fulcrums on the magnitude of isosteric heat of adsorption. (c) 2006 Elsevier Ltd. All rights reserved.