SUMMARYThe conductivity of copper cyanide electrolytes, using sodium, potassium and mixed formulations, has been measured. An all-potassium solution was found to exhibit a higher conductivity than a sodium solution of the same molarity, but the difference was relatively minor. Additions of free cyanide also had only a small effect. However, when carbonate was added there was a large improvement in the conductivity of the potassium solution, but very little for sodium. The properties of the mixed solutions were intermediate.Anodic and cathodic polarization curves are presented for all these solutions. The results indicate that potassium formulations are generally superior for the cathodic processes, but that the opposite is true on the anodic side.It is suggested that the optimum formulation for a commercial electrolyte may be based on an economic assessment of the various competing factors.