Kinetic parameters for the reaction of OH radical ini-tiated atmospheric oxidation of (E)-2-pentenal were computed using ab initio methods, viz. G3MP2 cou-pled with conventional transition state theory with the Wigner tunnelling corrections in the temperature range 200–400 K. Every stationary point on the poten-tial energy surface was obtained at MP2 (FULL)/6-31G* level of theory. Arrhenius rate expression for the title reaction with G3MP2 theory was computed to be k = (2.57 ± 0.33) × 10 –13 exp[(1482 ± 53)/T] cm 3 mol –1 s –1 . The OH-driven atmospheric lifetime of (E)-2-pentenal in the Earth's troposphere was calculated to be 5 h, with diurnally averaged concentration of OH radicals taken as 1.6 × 10 6 mol –1 cm –3 . The results obtained are in good agreement with the experimental results.