Catalytic degradation of the mixture of polypropylene (PP) and polystyrene (PS) was investigated in a semi-batch reactor. For all the catalysts (HNZ, SA, HZSM-5) tested, the main degradation products were liquid oils with gasoline range carbon number distributions.A natural clinoptilolite zeolite (HNZ) showed as good catalytic performance as silica-alumina (SA). HZSM-5 catalyst produced the highest amount of gaseous products. Increase of degradation temperature resulted in a decrease of ethylbenzene and propylbenzene, but an increase of styrene. Thermogravimetric analysis revealed the interaction of PP and PS in the catalytic degradation.