Stacking interactions between aromatic molecules (benzene, p-cymene, biphenyl, and di- and tetrahydrogen anthracene) and G. C and A. T canonical Watson-Crick (WC) base pairs are explored. Two functionals with dispersion corrections: omega-B97XD and B3LYP-D3 are used. For a comparison also the MP2 and B3LYP-D3/PCM methods were used for the most stable pi-cymene... WC geometries. It was found that the stacking interaction increases with the size of pi-conjugation system. Its extent is in agreement with experimental finding on anticancer activity of Ru(II) piano-stool complexes where intercalation of these aromatic molecules should play an important role. The explored structures are considered as ternary system so that decomposition of the interaction energy to pairwise and non-additivity contributions is also examined. (C) 2014 Elsevier B.V. All rights reserved.