The kinetics and thermochemistry for the fundamental reactions involved in low temperature autoignition of 2-pentanone were investigated by computational methods. CBS-QB3, a complete basis set method, was employed to calculate the thermodynamic parameters for the various species involved. The present study involves the decomposition pathways of alkylperoxy (ROO center dot), hydroperoxyalkyl ((center dot)QOOH) and hydroperoxyalkylperoxy ((center dot)OOQOOH) radicals formed in 2-pentanone, as these radical intermediates are important for chain branching at low temperature combustion which can be useful in modeling the autoignition. 1,6 and 1,5 H-migration reactions are the most favorable channels for the decomposition of ROO center dot radicals to form their respective (center dot)QOOH radicals. 1,6 H-migration occurring in R1OO center dot and R3OO center dot radicals have 16.1 and 22.0 kcal mol(-1) as their energy barriers which are lowest when compared to the energy barriers for all the other reactions involved in the decomposition of these radicals. Similarly, in case of R2OO center dot and R4OO center dot radicals, the 1,5 H-migration reactions have very low barriers (20.7 and 18.8 kcal mol(-1)) respectively. For (center dot)OOQOOH radicals, the peroxy radical interconversion ((center dot)OOQOOH to HOOQOO(center dot)) has lower energy barriers (10.4 to 14 kcal mol(-1)), but the decomposition proceeds with either HO2 center dot-elimination or other H-migration reactions. Rice-Ramsperger-Kassel-Marcus (RRKM) calculations were performed to study both the temperature and pressure-dependent rate coefficients in the temperature range of 400 - 1500 K and the bath gas pressures of 0.01 atm to 100 atm. (C) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.