Preferential solvation ofbis-1,10-phenanthroline-bis-cyanoiron(II) was investigated in aqueous acetone and 2-methoxyethanol binary mixtures. The solvatochromic behaviour is discussed in terms of donor and acceptor numbers. The thermodynamic model ofFrankel was used to treat preferential solvation in the binary aqueous 2-methoxyethanol mixtures and reveals that preferential solvation by the organic solvent occurs. The preferential solvation constant at 298.15K was found to be equal to 3.30±0.039, and the free energy of preferential solvation amounts to 2.96kJ·mole−1.