Crystals of Na zeolites were crushed using progressive high energy ball milling. A thermodynamic scale of the strength of Lewis acid and Lewis base sites of these samples was obtained by heat flow microcalorimetry. The collapse of the zeolite crystal caused a decrease in the number and strength of both Lewis acids and Lewis bases. It was however observed that the Lewis acid strength is strongly crystallinity dependent whereas the Lewis base strength is less so. Combined with XPS results, supporting evidence for Beren and Dubsky’s theoretical calculation results was obtained : the extraframework Lewis acids (Na cations) are remarkably influenced by the long-range stabilization effect of crystal zeolites, yielding then a higher strength of Lewis acid.