A kinetic model has been developed for the thermal decomposition of vinyl bromide at temperatures below approximately 750 K. The decomposition is initiated by two channels, a pressure dependent molecular channel, C2H3Br + M --> C2H2 + HBr + M, and a free radical channel, 2 C2H3Br --> C2H3 + C2H3Br2. The molecular channel is sccond-order overall at all the temperatures and pressures investigated. The temperature dependence of the rate constant for this reaction when vinyl bromide is M is given by ln(k(1a)) = 35.7 +/- 5.4-29.8 x 10(3)(+/-12%)/T. This leads to a preexponential factor of 3 x 10(15) L mol(-1) s(-1) and an activation energy of 248 kJ mol(-1). When M is argon, the preexponential factor is 2 x 10(8) L mol(-1) s(-1) and the activation energy is 153 U mol(-1) +/-23%. The temperature dependence of the free radical decomposition step is given by ln(k(2)) = 17.3 +/- 3.2 - (17.3 x 10(3) 13%)/T, giving a preexponential factor of 3 x 10(7) L mol(-1) s(-1) and an activation energy of 144 U mol-1. The model also provides kinetic data for the abstraction of hydrogen from vinyl bromide by C2H3 radicals, C2H3 + C2H3Br --> C2H4 + C2H2Br. The temperature dependence of this reaction is given by ln(k(3)) = 28.7 +/- 3.1-9.7 x 10(3)(+/-22%)/T, leading to a preexponential factor of 3 x 10(12) L mol(-1) S-1 and an activation energy of 81 kJ mol(-1).