Abstract: The extraction behaviour of indium with dimethylheptyl acetamide from hydroch-loric acid medium has been studied. The extractability is found to increase with the concentration of HCl. It is confirmed by an application of the slope method and chemical analysis that the extraction of In with N₅₀₃ from hydrochloric acid solution can be represented as follows: The solvation number n of the extracted species varies with the concentration of hydrochloric acid. IR and NMR data show that the indium is extracted in the form of HInCl₄ into the organic phase of N₅₀₃. Under the condition of [HCl]<2N the extract-ability of galliun, Indium and thallium with N₅₀₃ was found to be in the following order:Tl(Ⅲ)>Ga(Ⅲ)>In(Ⅲ)