Liquid/liquid interfaces can undergo spontaneous emulsification when a common-ion is distributed between both phases. By careful selection of electrolyte and solvent, stable nano-sized water-in-oil emulsions containing electrolyte can be produced. The emulsification process can be monitored indirectly via transient open circuit potential measurements using an electrochemical measuring cell, initially poised at equilibrium, within the organic phase. Theoretical analysis of experimental data indicates that the interfacial emulsification process is probably controlled by diffusion.