AbstractWe present a kinetic study of the reactions of ground‐state sodium atoms with the molecules CH3F, CH3Cl, CH3Br, HCl, and HBr at elevated temperatures (537–966 K). Na(32S1/2) was generated by the pulsed irradiation of various sodium halide vapors and monitored by time‐resolved atomic resonance absorption of the unresolved D‐lines at λ = 589 nm [Na(32PJ) ← Na(32S1/2)] in the “single‐shot mode.” The photoelectric signals were amplified without distortion, captured, and digitized in a transient recorder interfaced to a microcomputer for data analysis. Absolute second‐order rate constants were measured at various temperatures in each case, yielding the following Arrhenius parameters (kRX=Aexp(–E/RT), errors 1σ):which constitute, to the best of our knowledge, the first direct measurements of these quantities. The reaction between Na and HBr demonstrated anomalous behaviour which is discussed in terms of potential surfaces that have been calculated previously for this type of collisional process. The data are compared with analogous results for Na + CF4, CF3Cl, and CF3Br and with single‐temperature measureme