This paper presents a semidetailed kinetic scheme for the oxidation of iso-octane (2,2,4-trimethyl-pentane). Both the low- and high-temperature primary mechanisms are reduced to a lumped kinetic model involving only a limited number of intermediate steps. This primary reaction scheme, similar to the one already presented for n-heptane [1], is flexible enough to maintain accurate prediction of intermediate components, heat release, and ignition delay times for a wide range of operating parameter;. General criteria for the reduction of intermediate species allow an efficient coupling with a detailed kinetic model of C-1-C-4 oxidation. Thermochemical oscillations and the negative temperature coefficient (NTC) region of the reaction rate of the low-temperature oxidation of iso-octane in a jet-stirred reactor are reproduced quite well by the model. Several comparisons with experimental data, obtained under very different operating conditions, including a shock tube, a rapid compression machine, dow and jet-stirred reactors, support the applicability of this model of iso-octane oxidation over a wide range of pressures, temperatures, and mixture compositions.