Speciation of Co(II), Ni(II), Cu(II) and Zn(II) with L-arginine as primary ligand (L) and succinic acid as secondary ligand (X) has been studied in various concentrations (0.0 -2.5% wyv) of the anionic surfactant solution maintaining an ionic strength of 0.16 mol dm À 3 (NaNO 3 ) at 303 K. Titrations have been carried out in the presence of different relative concentrations (M: L: X ¼ 1 : 2 : 2, 1 : 2 : 4, 1 : 4 : 2) of metal to L-arginine to succinic acid with sodium hydroxide as titrant. The trend of the variation in the stability constants with changing dielectric constant as well as mole fraction of the medium is explained based on the electrostatic interactions of the side chains of the ligands, charge neutralization, chelate effect, stacking interactions and hydrogen bonding. Distribution diagrams with pH at different compositions of surfactant and structures of plausible ternary complexes are presented.