Kinetics, mechanism and thermochemistry for the reaction between 4-picoline and OH radical are studied using the DFT methods MPWB1K and BB1K. Addition of OH radical to ring carbon sites and hydrogen abstraction reaction from all the potential sites are considered. Barrier heights and thermochemistry for all these addition and abstraction processes are calculated to identify the most reactive reaction channels in different temperature. The calculated total rate constant for the 4-picoline + OH reaction is in reasonably good agreement with the experimental value. However, contrary to the earlier reported results, our study shows that H-atom abstraction is also an important reaction channel for the 4-picoline + OH reaction even at 298 K. (C) 2009 Elsevier B.V. All rights reserved.