ABSTRACT MOISTURE isotherms and activation energies of limestone rocks were determined. The isotherms followed the classical Brunauer-Emeet-Teller (B.E.T.) sorption theory with v^ = 0.233 mg of water per g of rocks. Arrhenius temperature dependence was observed for the temperature dependent coefficient used in the B.E.T. model. The value of c^ in the Arrhenius equation was found to be 8.114x10-8 for adsorption with AH equal to 44.418 kJ/mole. Hysteresis was observed with c^ for desorption being 12.231x10-^.