The phase behavior of carboxylic acid/alkylamine mixtures in water is largely dictated by a proton transfer from the acid to the amine, which will lead to charged species. If the distribution of carbon atoms is unequal between the acid and the amine, the result will be an ionic surfactant with an organic counterion. In this work the phase diagram for the ternary system acetic acid-dodecylamine-water at 298.2 K has been determined. Dodecylamine forms a lamellar phase with water, but when,acetic acid is added up to an equimolecular ratio between acid and amine, three new phases appear. These phases are an isotropic solution phase, a hexagonal liquid crystalline phase, and a cubic liquid crystalline phase. These three phases are not able to incorporate any excess amine. The solution phase shows the existence of micelles, which are spherical at high dilution, but show an elongation close to the phase border to the hexagonal phase.