Biodiesel production by non-catalytic supercritical methyl acetate (SCMA) reaction has been developed and optimized in previous study using Jatropha oil as oil feedstock. The reaction produces fatty methyl acid esters (FAME) as well as triacetin as the co-product. Due to the requirement of high reaction temperatures in SCMA treatment, thus the thermal stability of methyl oleate and methyl linoleate which are the major FAME in SCMA was investigated at temperature ranging from 330°C to 420°C. In addition, thermal stability of triacetin which was utilized as fuel additive in biodiesel was also investigated. The results revealed that the thermal stability of poly-unsaturated methyl linoleate decreases dramatically as temperature is increased from 330°C to 420°C while degradation of methyl oleate was only significant at 390°C and above. Similar behaviour was also observed for triacetin which was found to degrade at high temperatures, resulting in low yield of biodiesel fuel even at optimum conditions.