Jatropha seed meal was extracted with n-hexane and the oil obtained leas found to have iodine value 157.37, acid value 5.61 and free fatty acid 2.70. The fatty acid profile of the oil showed that oleic acid (31.35%), palmitic acid (20.9%) stearic acid (15.68%) and caprylic acid (10.45%) were the major fatty acid components. The seed oil was epoxidised at 29degreesC using peracetic acid produced in situ by reacting hydrogen peroxide (30% v/v) with various amounts of glacial acetic acid. Barium, cadmium, lead and zinc soaps of the oils were prepared by metathesis in alcohol solution. Thermal degradation studies on poly (vinyl chloride) in the presence of Jatropha seed oil, the epoxidised oil and the metal soaps of the oils were carried out at various temperatures (170, 180 and 190degreesC) under oxidative and non-oxidative conditions. Changes in intrinsic viscosity and levels of unsaturation in the degraded polymer samples together with kinetic data (rate measurements at 1% conversion) were used to evaluate the relative stabilising effect of the additives on the thermal degradation of poly (vinyl chloride). It was found that although the values of the rate of dehydrochlorination were of about the same order of magnitude (10(-2)% min(-1)), the rates were relatively lower, and the time at which degradation reached 1% conversion considerably higher than the corresponding values obtained in the-absence of the additives. The data from solution viscosity measurements and from estimates of the level of unsaturation in the degraded polymer samples indicate that metal soaps of the oil exert stabilising effect on the oxidative and monoxidative thermal degradation of poly (vinyl chloride).