Adsorption cooling machines are thermally driven systems. Solar radiation, waste energy, as well as geothermal energy can be used to power these systems. Theoretical study and simulation work of adsorption-based cooling systems require the knowledge about the adsorption pair characteristics and capacities at different conditions of working pressures and temperatures. This information is obtained from the adsorbate–adsorbent equation of state. Various models and formulas represent the adsorption pair equation of state for different combinations of adsorbate and adsorbent can be found in the literature. Furthermore, these state equations include some coefficients which are determined experimentally for each combination of the adsorption pair. The present work introduces a review of various adsorption equations of state which have been adopted by different researchers in their study. Moreover, the corresponding experimentally evaluated coefficients, which are found in the literature, for each model and for a variety of working pairs are reported as well.