This study investigated the thermal stability of vitamin D fortified groundnut oil. Vitamin D extraction and quantification methods were optimized. The oil was tested for vitamin D concentration after heating to temperatures from room temperature to 140°C for an hour. Ascorbyl palmitate was found to be a more effective antioxidant than vitamin E for maintaining vitamin D levels, showing a two-fold increase in vitamin D concentration compared to vitamin E. Further studies could explore other antioxidants and oils for vitamin D fortification.