The structure, energetics, and vibrational properties of complexes between water and carbon monoxide have been investigated by second-order perturbation theory. The two previously accounted stable minima H2O-CO and H2O-OC have been studied employing several different basis sets in order to establish the basis-set dependent fluctuations of the computed molecular properties. The complexes are formed via an almost linear hydrogen bond, where carbon monoxide attached from the carbon end represents the most stable complex. The importance of electron correlation is emphasized due to the correlation-induced sign reversal of the CO dipole moment. Substantial perturbations in the vibrational fundamental modes are predicted upon complexation rising from the hydrogen bond formation. The perturbation theory of intermolecular forces within the supermolecular approach is applied in analysis of the interaction energy components. The anisotropic behaviour of the energy components and the n --> pi* electron density delocalization are addressed upon the interaction.