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Zeolites are crystalline, porous aluminosilicates; while a pure silicate structure is charge-neutral, the substitution of A13+ for Si4+ creates in the framework a negative charge, which can be compensated by a proton that acts as a strong, acid-donating Br0nsted site. Zeolites are widely used in industry, most commonly for catalysis and separations. Unfortunately, they have not yet been able to replace all homogeneous catalysts in industrial processes due to the difficulties in reactant and product diffu-sion to and from the zeolite surface in the absence of a solvent. However, it is believed that if we had a thorough understanding of how solid acids, especially zeolites, cat-alyze reactions, then we would be able to design heterogeneous catalysts to overcome these difficulties. The nature of the acid sites in zeolites and the factors contributing to enhanced catalytic activity have been the subject of much study in the literature. In particular, the issue of whether all of the acid sites in a particular zeolite are homogeneous or heterogeneous in acid strength requires the development of a systematic way to quan