The pyrolysis of n-butane, initiated by methyl radicals has been studied in the temperature range 750–1000 K and at pressures 0.08–0.13 bar in a quasi-wall-free reactor using laser heating by fast vibrational–translational (V–T) energy transfer. This is a convenient method to study homogeneous high-temperature kinetics since the reactor walls remain cold. The radial temperature distribution in the reactor has been investigated by four different methods: stationary heat balance, optical absorption, pressure rise, and the temperature dependence of the rate of an isomerization reaction. Methyl radicals were produced ia the fast thermal dissociation of di-tert-butyl peroxide and product analysis was performed by the use of GC-MS. The main products of the overall reaction of the model system (n-C₄H₁₀ + CH₃) were C₂H₄, C₃H₆, C₃H₈, whereas 1-C₄H₈, n-C₅H₁₂, iso-C₅H₁₂ were minor components, all showing a strong dependence on temperature. The product distribution and the temperature dependence were analyzed by a kinetic model of 61 species and 164 reactions developed for the high-temperature butane and the low-temperature n-pentane oxidation. Good agreement was found between our experimental investigations and the modeling. However, we had to slightly adjust the rate constants for the reactions

At a temperature of 1000 K we found a larger branching ratio of k₃/(k₃ + k₄) = 1/3 compared to 1/8 as extrapolated from low-temperature data. The total rate coefficient was found to be (k₃ + k₄) = 8 × 10⁹ cm³ mol⁻¹ s⁻¹ which is about 50% higher than the extrapolated values.