The dependence of the proton affinity of the single six-membered ring (S6R) as a zeolite unit on the number of added protons was revealed by means of the semiempirical PM3 method. The proton affinity values were found to obey the linear regression A(H) = 253.4-37.69N(H) kcal/mol (in Si6O6(OH)(12)) with a high correlation coefficient (r = 0.9991). It was shown that the calculated activation barrier for proton "hopping" from one oxygen atom to another in the pure silica cycle is low (similar to 25 kcal/mol).