Interactions of a series of indole-3-alkanoic acids (with n-alkanoic acid side-chains from C1 to C4) with iron(III) in acidic aqueous solutions have been shown to comprise two parallel processes including complexation and redox transformations giving iron(II) hexaaquo complexes. The structure and composition of the reaction products are discussed, as analysed using a combination of instrumental techniques including 57Fe Mössbauer, vibrational and 1H NMR spectroscopies.