The titled compound, Hg2[Fe(CN)5NO], was synthesized and studied by X-ray powder diffraction, infrared spectroscopy, Mössbauer spectroscopy, and atomic force microscopy. The results arising from this study indicate that this compound is anhydrous and crystallizes in the P222 orthorhombic symmetry. The unit cell parameters were quantified as a= 16.5905(9) Å, b = 12.3145(8) Å, and c = 8.7576(5) Å. The measured and calculated density values are Dm = 1.149g/cm3 and Dc = 1.145g/cm3, respectively, with Z = 2. © 2000 International Centre for Diffraction Data.