According to the theoretical prognosis based on the calculation of the degree of individual reaction behaiviour and on the degrees of reactions behaiviour in two-component mixes, titration of indium (III) ions by potassium dioctyldithiophosphate individually and in 18 two-component mixes with Hg₂ ²⁺, Hg²⁺, Ag⁺, Se (IV), Te (IV), Cu⁺, Pb²⁺, Sb³⁺, Sn²⁺, Tl⁺, Ni²⁺, As³⁺, Ga³⁺, Zn²⁺, Co²⁺ is possible. The possibility of titration of indium (III) ions by dioctyldithiophosphate, ditridecyldithiophosphate and dicyclohexyldithiophosphate of potassium has been experimentally proved. The comparison of analytical characteristics of titrants has allowed to choose two best ones for the determination of indium (III) ions, they are dioctyldithiophosphate and ditridecyldithiophosphate of potassium. The possibility of quantitative potentiometric determination of indium (III) ions in mixture with cerium (III) using potassium dioctyldithiophosphate and potassium ditridecyldithiophosphate as titrants has been experimentally confirmed. Indium (III) ions are titrated by both reagents quantitatively. The error of determination is less than 1%. Indium (III) ions form the most stable complexes with potassium dioctyldithiophosphate, and less stable ones — with ditridecyl- and dicyclohexyldithiophosphate of potassium, which is confirmed by the size of potential jumps.