A flow reactor operated at high pressure has been used to study the oxidation kinetics of selected North Sea light crude oils. Real consolidated reservoir rocks impregnated with oil were tested. A simple approach based on oxidation reaction kinetics was adopted throughout the course of this study to decouple the low temperature (LTO) and high temperature (HTO) reaction regimes and to determine the boundary between them. Reaction kinetic results for low temperature oxidation region are presented in this paper. (C) 2000 Elsevier Science Ltd. All rights reserved.