AbstractThe kinetics of the gas‐phase elimination of two 2‐haloethyl methanesulphonates were determined in a static system over the temperature range 310–380°C and pressure range 26–174 Torr. The reactions in seasoned vessels, with the free‐radical inhibitor propene and/or toluene always present, are homogeneous and unimolecular, and follow a first‐order rate law. The rate coefficients are given by the Arrhenius equations: for 2‐bromoethyl methanesulphonate logk1(s−1) = (11·70 ± 0·43)–(172·8 ± 4·8) kJ mol−1(2·303RT)−1and for 2‐chloroethyl methanesulphonate logk1(s−1) = (11·67 ± 0·50)–(173·9 ± 6·0) kJ mol−1(2·303RT)−1. The bromo compound was found to be more reactive than the chloro compound. At 340°C, for Brk1= 9·46 × 10−4s−1and for Clk1= 7·12 × 10−4s−1. Apparently, electronic