The fluctuating temperature field in a jet stirred flow reactor designed for chemical kinetic studies of hydrocarbon oxidation is investigated. In order 10 address both the question of the degree of micro-mixing and that of the turbulence/chemistry interaction, the present paper analyses and compares the fluctuating temperature structures inside this reactor for various situations. The experimental study is conducted by the technique of fine-wire thermoanemometry. The pdfs. spectra and the relevant time scales of the temperature field are determined. In parallel, the fuel conversion rates of propane oxidation in all the experimental conditions are determined from a simulation work which takes into account a detailed kinetic model previously established. The variation of the unmixedness and the time scales of the temperature field is compared for a wide range of parameters in the reacting and non-reacting cases. The discussion is conducted in terms of the ratio between the time scales of the scalar and dynamic fields and of a Damköhler number.