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The kinetics of the reaction between pinonaldehyde (C 10 H 16 O 2) and Cl atom were studied using high level ab initio G3(MP2) and DFT based MPWB1K/6-31 + G(d) and MPW1K/6-31 + G(d) levels of theories coupled with Conventional Transition State Theory in the temperature range between 200 and 400 K. The negative temperature dependent rate expression for the title reaction obtained with Wigner’s and Eckart’s symmetrical tunneling corrections are k(T) =(5.1 ± 0.56) × 10 −19 T 2.35exp[(2098 ± 2)/T] cm 3 molecule −1 s −1, and k(T) =(0.92 ± 0.18) × 10 −19 T 2.60exp[(2204 ± 4)/T] cm 3 molecule −1 s −1, respectively, at G3(MP2)//MPWB1K method. The H abstraction reaction from the –CHO group was found to be the most dominant reaction channel among all the possible reaction pathways and its corresponding rate coefficient at 300 K is k(Eckart’s unsymmetrical) = 3.86 ×10−10 cm 3 molecule −1 s −1. Whereas the channel with immediate lower activation energy is the H-abstraction from –CH- group (Tertiary H-abstraction site, C g). The rate coefficient for this channel is k Cg(Eckart’s unsymmetrical) = 1.83 ×10−15 cm 3 molecule −1 s −1 which is smaller than the dominant channel by five orders of magnitude. The atmospherically relevant parameters such as lifetimes were computed in this investigation of its reaction with Cl atom.