The electron paramagnetic resonance spectra of a number of copper complexes and of vanadyl acetylacetonate were measured in solution and in the vitreous state. By a judicious choice of various mixtures of solvents, good glasses could be obtained at low temperature, which exhibited spectra with very sharp lines. In a number of cases a complete analysis of the spectrum was possible. We were then able to calculate the magnetic parameters and some properties of the wave functions by assuming either D4h or D2h symmetry. It appears that the vitreous state is well suited for a study of ligand interaction. A hyperfine splitting due to the magnetic moment of nitrogen ligand atoms could often be observed in the vitreous state when it could not be observed in the liquid state. Relaxation of ligands is qualitatively discussed.