The present invention relates to the determination of intra- or intermolecular interaction between molecules in aqueous solution, the method comprising the steps of: (a) determining the dehydration of all atoms in the intermolecular interface, (b) adding the vacuum hydrogen bond energy, and (c) further adding the change in the free enthalpy of the interacting partners upon their interaction. The obtained results can be used for the prediction if and to what extent two molecules of various origin fit to each other.