The experimental study of the thermal degradation of methylethylketone (MEK) in flame conditions is undertaken to provide an experimental data base concerning Volatile Organic Compounds (VOCs) oxidation. The experimental set-up consists of the coupling of microprobe sampling with gas chromatography and mass spectrometry analysis. Temperature measurements are realized by the coated thermocouple technique. The addition of MEK to a reference methane / air flame induces (1) an enhancement of the C2and C3hydrocarbon oxidation pathways which points out the main role of CH3and C2H5radicals, and (2) the formation of oxygenated intermediate compounds such aldehydes (CH2O, CH3CHO. CH3CH2CHO), alcohols (CH3OH, CH3CH2OH) and ketones (CH3COCH3, CH3COCHCH2, CH3CH2COCH2CH3, CH3COCH2CH2CH3). The peak mole fraction of these intermediate species increases with the amount of MEK added to the methane / air flame. The experimental results are discussed to point out the kinetic processes involved in the high temperature oxidation of MEK which may contribute to the development of a detailed chemical mechanism.