A systematic study of the preparation of methylsalicylatocopper(II) complexes with or without N-donor ligand has resulted in three new dimeric complexes formation. The investigation has been targeted to two main aspects: the conditions of dimeric complexes preparation and the properties of obtained products. The common stoichiometric formula for all three complexes is Cu(x-MeSal)2(H2O)(ACN)z (where x-MeSal = 3- or 4-methylsalicylate anion, ACN = acetonitrile and z = 0, 1). Used spectral measurements mainly EPR spectroscopy gave the proof about the existence of dimeric “paddle-wheel” units in all three complexes. Moreover, it was concluded that acetonitrile molecules are more probably bonded to copper(II) atoms in apical positions of dimeric units. The water molecules are in coordination sphere only in the case when acetonitrile is not present. However data show that presence of 4-methylsalicylate anions led to strengthening of Cu-N bonds.