Abstract: Process for the synthesis of ZMS-5 zeolites essentially consisting of: a. preparing two aqueous solutions of sodium aluminate and silicate; b. putting the two solutions in contact with each other under stirring at room temperature; c. adding a solution of a mineral acid to solution (a) or to solution (b) or to solution (a)+(b), in such a quantity that the molar ratio OH?/H2O ranges from 0.02 to 0.03; d. adding a quantity of water sufficient for maintaining fluid the reacting mixture and the molar ratio OH?/H2O from 0.017 to 0.022; e. pre-heating the final mixture obtained at the end of steps (a)-(d) at a temperature ranging from 20 to 60° C.; and f. heating the mixture, under stirring, at a temperature ranging from 100 to 200° C.