A micro-emulsion and a method of making the micro-emulsion are described. The micro-emulsion composition includes more than about 50 vol % of an oil phase and polar structures. The oil phase comprises a hydrocarbon component and a co-solvent, and the polar structures comprise an ionic liquid. The ionic liquid comprises a halometallate anion and a cation which is at least slightly soluble in the hydrocarbon component or in the co-solvent. 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, and the co-solvent is miscible in the hydrocarbon.

The present invention relates to a catalytic composition in the form of what is known as a Pickering emulsion, said composition comprising a first non-aqueous liquid phase L1 comprising hydrocarbon compounds, within which droplets of a second liquid phase L2 are stabilized by solid particles, said second liquid phase L2 comprising at least one ionic liquid of formula Q.sup.+A.sup., Q.sup.+ being an organic cation and A.sup. being an anion, and in which a Brnsted acid HB is dissolved.