Liquid-liquid equilibrium data of three systems containing surfactant polyoxyethylene cetyl ether (with abbreviation name Brij 58) and three salts, (NH4)(2)HPO4, NH4H2PO4, and KH2PO4, were measured at 298.15 K. Then the binodal curves were described using two three-parameter equations and the tie lines were described using four two-parameter equations. The best equations to correlate the binodal curves and the tie lines for these systems have been reported. Additionally, the effects of the salt type on the phase diagrams have been discussed.