IsoThermal crystallization kinetics, melting, structure and Dynamic mechanical properties of a polypropylene (PP) random copolymer were studied. In order to study the effect of cooling rate on melting, two different cooling rates were applied to the samples. While water cooled samples revealed a broad single melting endotherm with a-crystalline structure, the slow cooled samples showed a shoulder at lower temperature followed by a sharp melting endotherm and a mixture of a and g-crystalline phases. The effect of annealing on log E of the b-relaxation for the PP copolymer showed that the b-transition increased in intensity with increasing annealing temperature. No considerable difference was found in the activation enthalpy of relaxation, ΔH, values for the annealed compared to that of the water cooled samples using the Arrhenius equation. The isoThermal crystallization kinetics was also studied for PP and the values of nucleation constant, Kg, and end-surface free energy of the crystal growth, se, were calculated using Lauritzen-Hofffman theory.