Abstract: The extraction behaviors of iron (Ⅲ) with N,N-di(1-methylheptyl) acetamide (N503) in hydrochlorie acid medium, including equilibrium time, the effect of addi-tive agents and acidity, and extraction capacity have been described. The equation of extraction reaction has been deduced through a study on the equilibrium as where S refers to the extractant. The extrraction constant, Kex has been estimated as 10^2.19±0.04 (25℃, μ=4M). By means of both elemental analyses and thermal analysis, the composition of the coordination compound of iron(Ⅲ)obtained by saturation extraction has been identified as HFeCl₄•2S. The species of coordination compound investigated by magnetic moment.UV and IR spectra measurements can be expressed as(H⁺•2S)(FeCl₄^-).