Electrochemical machining allows for the rapid processing of complex geometries on difficult to machine materials. However, over time electrolyte performance degrades and impacts the metal removal rate which impacts finished machined geometry. We have evaluated electrolyte degradation to develop methods to monitor and control electrolyte composition for electrochemical machining processes. Electrolytes containing sodium nitrate, sodium chloride, and mixtures of the two were evaluated during the machining of 4340 steel. Linear sweep voltammetry methods have been developed to monitor changes in electrolytes as a function of machining time. These changes have been correlated with composition, pH, and conductivity of the electrolyte and the surface finish and material removal rate to understand the general health of the electrolyte throughout the machining process. The methodology allows for electrolyte recycling and replenishment during large scale machining.