The pulsed laser photolysis/pulsed laser-induced fluorescence technique has been applied to obtain rate coefficients for OH+CH3C(O)CH3 and CD3C(O)CD3 of k(H)(298-832 K) = (3.99+/-0.40) x 10(-24)T(4.00) exp(453+/-44)/T and k(D)(298-710 K) = (1.94+/-0.31) x 10(-21)T(3.17) exp(-529+/-68)/T cm(3) molecule(-1) s(-1), respectively. Three pathways were characterized via the CBS-QB3 ab initio method to obtain complete basis set limits for coupled-cluster theory. Addition to form CH3C(O)(OH)CH3, followed by dissociation to CH3+CH3C(O)OH, is negligibly slow. Variational transition state theory reveals that the dominant products are CH3C(O)CH2+H2O formed by direct abstraction at higher temperatures and via a hydrogen-bonded complex below about 450 K. Inclusion of tunneling gives good accord with the observed kinetic isotope effect down to about 250 K. (C) 2003 American Institute of Physics.