The extraction of lactic acid (HL) from aqueous solutions by Alamine 336 (B) dissolved in toluene was studied. Experiments were performed in the temperature range of 25-60 degrees C and for two amine concentrations of 20 and 40% (v/v) in toluene. The extent to which the organic phase (amine + toluene) may be loaded with lactic acid is expressed as a loading ratio, Z = C(<(HL)over bar>)/C-B. Z values are independent of the amine concentration and, hence, the extracted complex contains only one molecule of amine. Z decreases with increasing temperature. Experimental results indicate that the system presents overloading, i.e. Z > 1. The extraction equilibrium may be interpreted as a result of consecutive formation of three acid-amine species with stoichiometries of 1:1, 2:1 and 3:1.