The role of calorimetry in adsorption is shortly reviewed. The differences between calorimetric adsorption heats and those
calculated from Clausius-Clapeyron equation for the systems ethanol-activated carbons are presented. Obtained results, together
with the results presented previously for other adsorbates, confirm that calorimetry is indispensable for a real thermodynamical
description of the adsorption process in this type of system.