Gas-phase reaction of CHF3 (HFC 23) with CH4 in the presence of CBrF3 (halon 1301) to produce CH2=CF2 (VDF) is presented. Experiments were carried out in a plug-flow reactor at temperatures between 873 and 1173 K. Under these conditions, CH2=CF2 was a dominant product observed, with CH2F2, C2H2, CH2CHF, C2F4, C2H6 and CHFCF2 also detected. In the presence of less than 6000 ppm of CBrF3, the rate of formation of CH2=CF2 is significantly enhanced, and a much lower rate of formation of the major by-product, C2F4 is observed. Further increasing the proportion of CBrF3 in the feed resulted in an even higher rate of formation of CH2=CF2. Experimental results are fitted very well by a model derived from the NIST and GRI-Mech 3.0 mechanisms, modified to include additional published kinetic data. (C) 2010 Elsevier B.V. All rights reserved.