The thermal degradation of isotactic and atactic polypropylene was investigated in bulk and in solution. The degradation in bulk was studied with thermogravimetric analysis, and the degradation in solution was studied by the dissolution of the polymer in paraffin oil. The degradation in solution was investigated from 230 to $350^ \circ C$. The effect of the hydrogen donor on the degradation of the polymer in solution was also studied at $350^ \circ C$. Continuous distribution kinetics were employed to model the degradation kinetics for the degradation in solution. The rate coefficients were obtained, and the activation energy was calculated from an Arrhenius plot