Spontaneous ignition or spontaneous combustion is a well-known chemical phenomenon in fire investigations. Spontaneous ignition is defined as the “chemical or biological process that generates sufficient heat to ignite the reacting material." In such fires, vegetable (or animal) oil is sometimes suspected of being the substance that underwent spontaneous ignition. Many fires caused by self-heating processes have been documented in research. Vegetable oils are likely to undergo auto-oxidation, which produces self-heating that, in some instances, may lead to spontaneous ignition. This paper intends to introduce the concept of self-heating and spontaneous ignition of vegetable (and animal) oils through a review of the literature. In addition, a forensic approach to the examination of vegetable (and animal) oil residue (VOR) is presented. Tables, references