AbstractThe kinetics of 2‐bromo‐3‐methylbutyric acid in the gas phase was studied over the temperature range of 309.3–357.0°C and pressure range of 15.5–100.0 torr. This process, in seasoned static reaction vessels and in the presence of the free radical inhibitor cyclohexene, is homogeneous, unimolecular, and follows first‐order rate law. The observed rate coefficients are represented by the following Arrhenius equations: logk1(s−1) = (12.72 ± 0.25) − (181.8 ± 2.9) kJ mol−1(2.303RT)−1. The primary products are isobutyraldehyde, CO, and HBr. The polar five‐membered cyclic transition state type of mechanism appears to be preferred in the dehydrohalogenation process of α‐haloacids in the gas phase.