Understanding of the sensitivity of the red-action potential of Cerium(IV) cations to ligand field, strength has yet to benefit from systematic variation of the ligand environment. Detailed analyses for a series of seven cerium(W) tetralds(pyridyl-nitroxide) compounds and their cerium(III) analogues in varying ligand field Strengths are presented. Electrochemical, spectroscopic, and computational results reveal a dose correlation of electronic properties with ligand substituents. Together with electrochernical data for reported eight-coordinate compounds, DET calculations reveal a broad range of the cerium(IV/III) redox potentials correlated to ligand field strengths, establishing a semiempirical, predictive model for the modulation of cerium redox thermodynamics and ligand field strengths. Applications over a variety of scientific disciplines make use of the fundamental redox thermodynamics of cerium. Such applications will benefit from a combined experimental and theoretical approach for assessing redox cycling of cerium compounds.