The selective separation of toluene from heptane is investigated using unsubstituted cyclodextrin (alpha CD), cyclodextrin (alpha CD) and also with two substituted CDs as a carrier in oil/water/oil-type emulsion liquid membranes. The separation factor for toluene to n-heptane is evaluated from the extraction of an equimolar mixture of toluene and n-heptane. ss CD shows the highest selectivity followed by alpha CD, hydro-propyl-alpha and hydroxypropyl-ss CD. The separation performances, represented by the permeation rate and separation factor, are analyzed systematically by varying the operating parameters: contact time, concentration of carriers, volume fraction of the membrane phase, and the relative amount of solvent. In this paper the effects of carriers and interfacial tension on dispersed phase drop size, internal droplets size, and size distribution are also systematically investigated.