The mean enthalpy change (ΔH) for the adsorption process of MB and EY as calculated were 71.62 kJ mol−1 and 93.18 kJ mol−1, respectively. This positive value of ΔH reveals that the process of dye adsorption is endothermic in nature similar to most of the processes of adsorption involving activated carbon. The relatively high values of ΔH are may be due to the formation of strong chemical bonds between the dye molecules and functional groups of the adsorbent surface.