A catalyst composition including the compound of Formula I as an internal electron donor, wherein: R1, R2, R3, R4, R5 and R6 are independently selected from a group consisting of hydrogen, straight, branched and cyclic alkyl and aromatic substituted and unsubstituted hydrocarbyl having 1 to 20 carbon atoms; R7 is selected from a group consisting of straight, branched and cyclic alkyl and aromatic substituted and unsubstituted hydrocarbyl having 1 to 20 carbon atoms; and R8 is selected from a group consisting of aromatic substituted and unsubstituted hydrocarbyl having 6 to 20 carbon atoms. Also disclosed is a process for preparing said polymerization catalyst composition; a polymerization catalyst system comprising said catalyst composition, a co-catalyst and optionally an external electron donor; a polyolefin obtainable by the process; and use of the compound of Formula I as in internal electron donor in catalysts for polymerization of olefins.