The present invention relates to a catalyst product for cracking of heavy hydrocarbon feed stocks predominantly in to light olefins and processes for preparing the catalyst. More specifically the present invention relates to a process of preparing Fluidic Catalytic Cracking (FCC) catalyst additive composition. The FCC catalyst additive composition of the present invention is a LPG selective catalyst particles comprising a medium pore zeolite bonded with clay-phosphate-silica-alumina binder. The catalyst of the present invention exhibits improved selectivity towards high value components like propylene and gasoline and suppressing low value components like dry gas and bottoms.