2,4,6-Trimorpholino 1,3,5-triazine (KD) gives metal complexes with Al(III), Fe(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Ce(III), and Pb(II). Only Fe(III) complex species absorb in the ultraviolet region. We have determined the best conditions for titrating Fe(III) alone or with cationic surfactants: benzyl dimethyl tetradecyl ammonium chloride (BDTA) and cetyl pyridinium chloride (CPC), in water-ethanol medium (50:50, v/v). The optimum experimental conditions for the complex-formation reactions and the composition of Fe(III) complexes are described. A simple method is proposed for determination of Fe(III) without previous separation, in presence of other ions and mainly a large quantity of Fe(II). To cite this article: N.