The rate coefficient for the gas-phase reaction of Cl atoms with ethyl formate was measured over the temperature range of 268-343 K using relative rate methods, with ethyl chloride as a reference compound. The temperature dependent relative rate coefficients for the ethyl formate + Cl reaction were measured, and the modified Arrhenius expression kethyl formate(268-343) = (2.54 ± 0.57) × 10(-23) T(4.1) exp {-(981 ± 102)/T} cm(3) molecule(-1) s(-1) was obtained with 2σ error limits. The room temperature rate coefficient for the title reaction is (9.84 ± 0.79) × 10(-12) cm(3) molecule(-1) s(-1), which is in good agreement with reported values. To complement the experimental measurement, computational methods were used to calculate the rate coefficient for the ethyl formate + Cl reaction atoms using canonical variational transition state theory (CVT) with small curvature tunneling (SCT) and the CCSD (T)/cc-pVDZ//M062X/6-31+g(d,p) level of theory. The temperature dependent Arrhenius expression was obtained to be 2.97 × 10(-18) T(2.4) exp[-(390/T)] cm(3) molecule(-1) s(-1) over the temperature range of 200-400 K. The thermodynamic parameters and branching ratio were calculated. Also, the atmospheric lifetime and global warming potentials (GWPs) were calculated for ethyl formate.