Rigid PVC pellet was treated at 150-250°C in 0∼7M NaOH solutions for 0∼12h. The degree of dehydrochlorination increased with increasing reaction temperature, and reached about 100% at 250∼C over 3h. A porous char, 2μm pore size, was produced. The dehydrochlorination proceeded by a first order reaction in the alkaline solution. Maximum rate of the dehydrochlorination for rigid PVC was at 3M NaOH. The apparent activation energy was 96 kJ mol-1 in 3 M NaOH for rigid PVC.