The synthesis and crystal structure for the title compound, hexaaquahexakis(μ-2-hydroxybenzenecarbohydroxamato)bis(2-hydroxybenzenecarbohydroxamato)tetraindium(III) tetranitrate 8.57-hydrate + unknown solvent, [In₄(H₂shi)₈(H₂O)₆](NO₃)₄·8.57H₂O·solvent, where H₂shi⁻ is salicylhydroximate (C₇H₅NO₃), are reported. The complex cation of the structure, [In₄(H₂shi)₈(H₂O)₆]⁴⁺, is a dimer with a step-like topology and possesses an inversion center that relates each [In₂(H₂shi)₄(H₂O)₃]²⁺ side of the complex cation. Each In^III ion is seven-coordinate with a pentagonal–bipyramidal geometry, and the salicylhydroximate ligands have a 1− charge as only the oxime oxygen of the ligand is deprotonated. Four interstitial nitrate anions maintain the charge balance of the compound. One of the nitrate anions (and its symmetry equivalent) is disordered over two different orientations with an occupancy ratio of 0.557 (7) to 0.443 (7). The interstitial solvent water molecules show substantial disorder. Approximately 8.57 water molecules per formula unit were refined as disordered and partially occupied, while a suitable model could not be devised for the other extensively disordered solvent molecules (water and possibly methanol as this was the synthesis solvent). Thus, these latter solvent molecules were instead treated with the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18.] as implemented in the program PLATON, and the procedure corrected for 151 electrons within solvent-accessible voids of 367 ų.