The present invention relates to a catalyst composition comprising the compound represented by Formula (I) as an internal electron donor, Formula I wherein: R1, R2, R3, R4, R5 and R6 are the same or different and 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; N is nitrogen atom; O is oxygen atom; and C is carbon atom. The present invention also relates to a process for preparing said polymerization catalyst composition and to a polymerization catalyst system comprising said catalyst composition, a co-catalyst and optionally an external electron donor. Furthermore, the present invention relates to a polyolefin obtainable by the process according to the present invention and to the use of the compound of Formula I as in internal electron donor in catalysts for polymerization of olefins.