Rate constants for overall H-atom abstraction by hydroxyl radicals from C.dbd.H and O.dbd.H bonds are estimated for alkanes, haloalkanes, aldehydes, ketones, ethers, alcohols, nitriles, and nitrates over the temperature range 250-1000 K. These estimated rate constants utilize the modified Arrhenius expression k = A''T2e-E/T in combination with the recommendations given in the recent review and evaluation of OH radical kinetics of Atkinson. This estimation procedure gives good agreement, generally to within better than a factor of 2, of the estimated rate constants with these recommendations.