Niobium(IV) methoxide was synthesized by prolonged electroreduction of niobium pentachloride in methanol. Electron paramagnetic resonance spectra at room temperature and 77 K show the expected 10-line patterns of93Nb atand ΔMs = 2 absorptions indicating the presence of dimer species. The spectroscopic parameters obtained in the presence of a series of phosphorus donor ligands are presented and discussed in terms of mononuclear and dinuclear structures.