This study investigated the effects of added phenolics on the storage stability of avocado and coconut oils. Avocado and coconut oils in the absence (control oil) and presence (treated oil) of caffeic acid (CA) or p-coumaric acid (pCA) were stored at 20 and 60 °C for 50 days. The total phenolic content, peroxide value, p-anisidine value (p-AV), free fatty acids (FFAs) and FA composition of the obtained oils were examined on days 0, 7, 15, 23, 35 and 50. Results showed that storage at 60 °C accelerated oil oxidation, and the CA or pCA helped preserve avocado and coconut oils to different extents. CA and pCA protected some desirable unsaturated fatty acids at 60 °C, but facilitated the hydrolysis of triglycerides. Substantially extractable phenolics were still detected in the treated oils after either storage. Incorporation of phenolics into oil products is feasible and beneficial for increasing oil stability and nutritional value.