Electron attachment to F2and NF3has been studied in an electron‐beam‐controlled gas‐discharge apparatus over a range ofE/P(2–10 kV/cm atm). These experiments were performed in gas mixtures containing small amounts of the halide molecules (≲1%) in an atmosphere of N2which was included to control the average electron energy. We obtained values for the rate constants for dissociative attachment to F2and NF3as a function of mixture temperature at 300 and 500 °K and applied electric field. These results compare favorably with the rate constants deduced from the absolute cross section for these compounds reported by Chantry.