The molar enthalpy of occlusion of the (lithium chloride + potassium chloride) eutectic salt in zeolite 4A at the salt melting temperature Delta(occ)H(m)(T-fus) was measured using differential scanning calorimetry. It was found that up to a mole fraction of the salt x = 0.931 in the (salt + zeolite) mixture, which is near the expected zeolite occlusion limit, Delta(occ)H(m)(T-fus) was negative and directly proportional tox. Thus, within this composition range, the partial molar enthalpy of occlusion of the (lithium chloride + potassium chloride) eutectic salt in zeolite 4A at the salt melting temperature is constant and equal to -(24 +/- 1) kJ . mol(-1).