The complex bimetallic salt [Cr(NH3)6][Ni(H2O)6]Cl5 · 1 2(NH4Cl) crystallizes in the space group Fd3 with a = 20.440(2) Å and Z = 16. The crystal and molecular structures have been determined from single crystal data, despite a systematic twinning (RF = 0.037, RI = 0.041 for 1065 reflections). The spatial arrangement consists in discrete [Cr(NH3)6]3+, [Ni(H2O)6]2+, Cl-, and NH+4 ions, held together by ionic forces and by a network of hydrogen bonds. Both chromium and nickel ions are in octahedral sites. Structural correlations with related compounds are examined. © 1990.