The effects of tetraalkylammonium ions on the stability of dilute o/w emulsions were investigated with turbidimetric measurements. Large tetraalkyl-ammonium ions were found to induce flocculation of emulsions stabilized by ionic emulsifiers at concentrations 3 order of magnitudes lower compared to sodium ions. Emulsions stabilized by nonionic surfactant were also destabilized by low concentrations of organic ions. Inclusion complex formation of sodium ions with a crown ether, was found to drastically decrease the stability of the emulsion. All these observations demonstrate the importance of ion size and ion hydro--phobicity on the stability of emulsions in presence of electrolyte. NMR self-diffusion measurements in micellar systems, monitoring ion-emulsifier interactions, and studies of the phase behaviour of the emulsifier/organic ion systems have been performed in an attempt to rationalize these observations.