Abstract: The present, invention relates to a process for the production of additives for catalysts for fluid catalytic cracking (FCC) based on zeolite that is selective for light olefins, with the aim of increasing the yields, in FCC units, of liquefied petroleum gas (LPG) and light olefins, of high added value, among others propene and isobutene. This invention provides a method of preparation of catalytic compositions, starting from zeolite modified with phosphate and alkaline-earth metal, that leads to the production of an additive with better performance than the additives, of similar compositions, obtained by other methods of the prior art. The process can be regarded as a development in relation to other processes, as it promotes interaction between the zeolite that is selective for light olefins and its activator, reagent “X”. For this, a separate stage is used during the sequence of stages in the preparation.