A series of mononuclear catecholato complexes of general formula LMoO(cat) (L = hydrotris(3,5-dimethyl-1-pyrazolyl)borate) have been prepared and characterized by cyclic voltammetry, IR, UV/vis, and EPR spectroscopy. The potential of the Mo(V/IV) redox couple is sensitive to the catechol substituents, but the nearly axial EPR parameters are primarily governed by the coordination environment about the metal and are similar for all of the compounds.