AbstractThe equilibrium molalities of In3+in extraction reaction: In3+(aq)+3HOx(org) = In(Ox)3(org) + 3H+(aq) were measured at ionic strengths from 0.13 to 2.54 mol·kg−1in the aqueous phase containing Na2SO4as the supporting electrolyte and at constant initial molality of extractant, HOx, in the organic phase at temperatures from 278.15 to 308.15 K, where HOx and Ox mean 8‐hydroxy‐quinoline and its anion, respectively. The standard extraction constantsKat various temperatures were obtained by two methods proposed in our previous