The electron‐attachment rate constants of HCl diluted in Ar and N2were measured as a function of the reduced electric fieldE/N. These data were converted to the electron‐attachment cross section of HCl using the electron‐energy distribution functions of pure Ar and N2. The dependence of the electron‐attachment rate constant and the mean electron energy on the fraction of HCl in each buffer gas was investigated. A comparison of the current result with both available experimental data and theoretical calculations is made.