Solubility and liquid-liquid phase equilibrium data for the ternary system water-phosphoric acid-2-ethyl-1-hexanol at 25 degreesC have been determined. Hand's method and the UNIQUAC equation have been used to correlate the experimental tie lines. On the other hand, a horizontal liquid-liquid contactor with constant interfacial area has been developed in order to obtain mass transfer coefficient values. Experimental results show that the equipment is useful for mass transfer coefficient determination.