Generation IV Molten Salt Reactors' (MSRs) liquid salt fuel system and fast reactor technology simultaneously address concerns over waste, safety, and nonproliferation. However, work is needed to understand the impacts of the fuel salt systems and subsequent corrosion of their containment. Electrochemical and spectroscopic methods can probe several fundamental aspects of complicated molten salt chemistry so long as the electrodes can both withstand the molten salt environment for prolonged periods of time and provide a mechanism for the transmission of light. Boron-doped diamond (BDD) is expected to be resilient against harsh environments, given its sp³-carbon structure. As such, BDD could potentially be used for characterization of dynamic molten salt fuel matrices, and potentially in situ corrosion control and monitoring in the core containment vessels. However, the corrosion of BDD in molten salt is not yet fully understood, nor is free-standing BDD an inherently optically transparent material for spectroelectrochemistry (SEC) methods. These measurements provide values for formal reduction potential, diffusion coefficients, Gibbs free energy, enthalpy, and entropy of the systems which can be compared to the traditional electrochemical techniques that often struggle to fully capture the complex actinide redox behavior occurring in MSR fuels. In this study, we investigated the europium(II/III) redox couple with free-standing BDD electrodes with electrochemical techniques like cyclic voltammetry, chronoamperometry, and chronoabsorptometry to determine formal reduction potential, electron transfer stoichiometry, diffusion coefficients, and electroactive surface area of the BDD. Scanning electron microscopy and x-ray photoelectron spectroscopy were used to identify topographical and surface changes in diamond crystal structures. Measurements provided values comparable to expected literature values and, in general, little corrosion or change to the BDD was observed. As a result, we present a novel optically transparent free-standing BDD electrode design for SEC measurements in harsh molten salt analytes. This ‘minigrid’ BDD successfully performed a variety of spectroscopic and SEC measurements in both aqueous and molten salt environments, and will next be applied to molten uranium and plutonium fuel matrices with various fission and corrosion products. This work advances the understanding of MSR chemistry while simultaneously proving the applicability of BDD as electrode material for harsh environments.