The gas phase pyrolysis and oxidative pyrolysis of CH3Br was studied experimentally in a flow reactor under atmospheric pressure, at temperatures in the range 500-800 °C and at reaction times in the range 0.6-1.5 s. Gas samples were withdrawn from within the reactor using a heated micro-probe and were analyzed by a computer controlled gas chromatograph(GC)/massspectrometer(MS) system. Pyrolysis products were primarily CH4, C2H4, CH2Br2and C2H2, and HBr and H2as determined from atom balances. In addition, trace levels of C6H6, C6H5Br, 1,2-C2H2Br2(Z and E), l,2-C2H4Br2were observed at higher temperatures. Coke formation was significant, with unaccounted carbon levels reaching 50% in some experiments. The major products in the oxidative pyrolysis process were CH4, C2H4, CH2Br2, CO and CO2, with the same trace species observed as in the case of pyrolysis. The presence of O2in the system did not significantly reduce coke formation.