Catalytic and thermal cracking of polypropylene was performed in a batch reactor. Effect of hydrochloric acid activation on kaolin clay, effects of catalysts (acid-activated clays), promoter (5 wt% Ni), and cracking temperatures on the liquid oil yield were investigated. Results show optimized liquid yield (71.9%) obtained at 470 degrees C with kaolin clay activated with 3 M HCl. Acid-activated catalysts were analyzed using XRD and the results reveal the reduction in peaks' intensities. Weight loss of polypropylene was investigated by thermogravimetric analysis. FTIR and GCMS techniques were employed to analyze the liquid products.