The complexes of acetone and 2-butanone with up to two water molecules hydrogen bonded to the carbonyl oxygen were studied computationally using Density Functional Theory at the B3LYP/6-311++G(d,p) level. Gas phase calculations were followed by optimizations in the solvent field, simulated with the Polarizable Continuum Model (PCM). Vibrational frequencies obtained with the help of empirical correlation agreed well with experimental spectra of HDO in aqueous solutions of the studied ketones. Accurate clustering enthalpies and free energies were obtained at various levels of theory, up to Coupled Cluster. Hydration free energies of the solutes were also calculated and compared with experiment. (C) 2009 Elsevier B.V. All rights reserved.