Aluminum and gallium isomorphs of omega zeolites in Na+, H+, and La3+ cationic forms were characterized by equilibrium sorption uptakes of different probe molecules such as water, cyclohexane, n-hexane, and benzene at 298 K at P/P-0 = 0.8 (2 h). Specific surface areas (BET) and void volumes were obtained by low-temperature (78 K) nitrogen sorption. Ammonia sorption isotherms in these zeolites have been measured in the temperature range of 323-523 K up to 400 Torr. The amount of ammonia retained irreversibly (on account of chemisorption) during desorption measurements was found to be correlated with the acidic character of the zeolite. The analysis of these isotherm data in terms of different isotherm models revealed satisfactory representation of Dubinin, Langmuir, Freundlich, BET, and Sips equations in the low-pressure region. Sorption models of Langumir and Volmer with and without sorbate-sorbate interaction show limited applicability of these models. All the zeolites were compared in terms of chemical affinity of the sorption. Isosteric heat computed from linear isosters revealed the surface heterogeneity. Qst values were found to decrease with the coverage.