Pyrolysis of brown grease has been shown to produce kerosene-like hydrocarbons as well as ketones. The process involves several different chemical reactions of the saturated and unsaturated fatty acid components. The yields and product distributions are dependent on the reaction temperature profile, a factor that must be considered in reactor and process design. In this paper we investigated the parameters of reaction temperature and time as brown grease was preheated and held at a set of temperatures before distillation of the kerosene-like hydrocarbons. It was found that the heating and temperature profile has a significant effect on the relative yields of reaction products.