[en] Reagent 3(2'-pyridylazo)-dihydroxypyridine (PADOP) has been synthesized for indium photometric determination. Sensitivity and contrast range of its interaction with indium were preliminarily determined by the Huckel MO LKAO calculation method. Experimentally ascertained analytic properties of the reagent agree satisfactorily with preliminary theoretical calculation prediction. The optimum conditions for indium - PADOP complex formation are as follows: pH 5.5-6.5, reagent concentration - 1.8x10^-4 mol/l and higher. The Berr law is observed when indium content is from 5 to 50 μg in 25 ml. Molar absorption coefficient of indium complex with PADOP is ε=4.56x10⁴