The distribution equilibria of In (III) 0.1 mmol/dm3 from HCI concentrated media (2.2-4 mol/dm3) with the commercial trialkylamine ADOGEN 364 dissolved in kerosene was studied. Due to the association processes that these type of extractants present in the organic phase, a preliminary study was performed by means of a two phase potentiometric titration with the aim of determining the degree of association and the formation constants of the aggregates. The extraction of HCI is explained on the basis of the formation of ADGHCI and (ADGHCI)2 species. With the data obtained the solvent extraction process of In(lll) is discussed. The presence of (ADGHCI)lnCl3, (ADGHCI)2lnCl3 and ((ADGHCI)2)2lnCl3 species in the organic phase allows to explain more satisfactory the experimental results obtained. For all the proposed equilibria the corresponding equilibrium constant is determined from the numerical analysis of the data with the use of the Letagrop-Zeta or Letagrop-Distr programs. © 1995, Taylor & Francis Group, LLC. All rights reserved.