The kinetics of the reaction between pinonaldehyde C₁₀H₁₆O₂ and Cl atom were studied usinghigh level ab initio G3(MP2) and DFT based MPWB1K/6-31+G(d) and MPW1K/6-31+G(d) levels of theoriescoupled with Conventional Transition State Theory in the temperature range between 200 and 400 K. Thenegative temperature dependent rate expression for the title reaction obtained with Wigner’s and Eckart’s symmetricaltunneling corrections are k(T)=(5.1 ± 0.56) × 10⁻¹⁹T^2.35exp[(2098 ± 2)/T] cm³ molecule^-1 s^-1, and k(T)=(0.92 ± 0.18) × 10^-19T^2.60exp[(2204 ± 4)/T] cm³ molecule^-1 s^-1, respectively, at G3(MP2)//MPWB1Kmethod. The H abstraction reaction from the –CHO group was found to be the most dominant reaction channelamong all the possible reaction pathways and its corresponding rate coefficient at 300 K is k_{Eckart’s unsymmetrical}= 3.86 ×10^-10 cm³ molecule^-1 s^-1. Whereas the channel with immediate lower activation energy is the H-abstraction from –CH- group (Tertiary H-abstraction site, Cg). The rate coefficient for this channel is k_{Cg(Eckart’s unsymmetrical)} = 1.83 ×10^-15 cm³ molecule^-1 s^-1 which is smaller than the dominant channel byfive orders of magnitude. The atmospherically relevant parameters such as lifetimes were computed in thisinvestigation of its reaction with Cl atom.