The chemical equilibrium of the reactive systems n-alkanol + alpha -methylstyrene double left right arrow alkyl cumyl ether (alkyl is ethyl, propyl, and butyl) was studied in the liquid phase in the temperature range (300 to 383) K using a cation exchanger as heterogeneous catalyst. Equilibrium ratios K-x obtained from concentrations of the reaction participants in the mixtures with an excess amount of alkanol are practically independent of the reactive mixture composition and can be identified with the thermodynamic equilibrium; constant K-a. Enthalpies of reactions Delta H-r(m)o of alkyl cumyl ether synthesis in the liquid phase were obtained from the temperature dependence of K-a and showed a good agreement with those reaction enthalpies derived from the values Delta H-f(m)o(l) of the reactions participants measured for alkyl cumyl ethers by combustion calorimetry. The standard molar enthalpies of vaporization of alkyl cumyl ethers were obtained from the temperature dependence of the vapor pressure measured by using the transpiration method. Resulting values of Delta H-f(m)o(g) were used to prove the consistency of the experimental data and to derive strain enthalpies of alkyl cumyl ethers. The strain effects were discussed in terms of deviations of Delta H-f(m)o(g) from the group additivity rules.