[en] Crystallization of aqueous solutions of equimolar quantities of NH₄ReO₄ and M(ReO₄)₃ with M = Sc and In at room temperature was used to prepare isostructural binary NH₄M(ReO₄)₄ · 4H₂O perrhenates. X-ray diffraction study was conducted for them. Tetragonal (sp.gr. P4n2) crystals NH₄M(ReO₄)₄ · 4H₂O (M = Sc, In) are characterized respectively by a = 12.439, 12.460, c = 6.114, 6.123 A, Z = 2, d_clc = 3.997, 4.199 g/cm³. M³⁺ and NH₄⁺ ions, forming the ordered motive of white tin and characterized by eightfold coordination by oxygen, are bonded into frame through bridge ReO₄ tetrahedrons and water molecules. 11 refs.; 2 figs.; 4 tabs