An isospecific metallocene catalyst was used for the synthesis of propene/alpha -olefin copolymers with a comonomer content up to 15 mole-%. The thermal behavior as well as the mechanical properties of the products were characterized. The aim of our work was the modification of polypropylene properties as well as the investigation of the influence of different alkyl side chains that were introduced by the copolymerization of propene with linear or branched alpha -olefins. A direct comparison is possible investigating copolymers with a uniform comonomer content of 10 mole-%. Ethyl side chains in propene/1-butene copolymers cause a minor change in properties whereas by incorporating longer side chains a broad property variation can be obtained.