A micro-emulsion and a method of making the micro-emulsion are described. The micro-emulsion includes a hydrocarbon component, an ionic liquid component, and a co-solvent. The ionic liquid comprises a halometallate anion and a cation. The micro-emulsion can optionally include a surfactant, and a catalyst promoter. The co-solvent has a polarity greater than the polarity of the hydrocarbon. The ionic liquid is present in an amount of about 0.05 wt % to about 40 wt % of the micro-emulsion.