Waste plastics make up approximately 20% of the volume of landifill material and almost 10% of the weight. These products contain substantial energy recovery value, and also represent a potentia!iy valuable source of feedstock raw material for additional plastics production. Controlled pyrolysis offers a method of converting raw, mixed waste plastics back into feedstock grade liquids by the application of heat in the absence of oxygen. However, chlorine from the thermal degradation of polyvinyl chloride (PVC) can contaminate the reclamed liquids making them more difficult and expensive for processing, and also produce a corrosive atmosphere which makes processing more expresive. This paper reports on a study of the impact of PVC on the thermal degradation rates other plastics including polypropylene (PP), polystyrene (PS), low-density polyethylene (LDPE), high-density polyethylene (HDPE) and polyethylene terephthalate (PET) in a thermogravimetric analyzer (TGA). Commodity plastics were mixed at various ratios with PVC and analyzed by means of their degradation rates to determine the kinetic rate constants which were compared to the rates obtained for the pure plastics. The values of the kinetic parameters for the pure compounds were all very close to, or within the ranges obtained from the literature. The results indicated that the decomposition behavior of the mixtures differed from those of the pure polymers. These deviations were greatest for mixtures of PVC with polyethylene terephthalate where it was determined that the dehydrochlorination step of PVC catalyzes the decomposition of PET. Pyrolysis of mixtures of PVC and polysteryne at temperatures between 200° C and 350° C result in incomplete dehydrochlorination. This results in more chlorinated compounds being released at higher temperatures.