Abstract: A system providing selective spin modification and reaction in an electrolytic cell. An electrolytic cell is coupled to a magnet that provides a level-splitting magnetic field in a region of electrolyte adjacent to a working electrode, thus establishing a spin resonance for an unpaired electron associated with a chemical species in the region of electrolyte adjacent to the working electrode. The working electrode carries an excitation current produced by a switching source or amplifier. The excitation current produces an alternating magnetic field adjacent to the working electrode that alters the spin state population density for the unpaired electron associated with a chemical species within the electrolyte, thereby enhancing or inhibiting the reaction of the chemical species during subsequent electrolysis.