The title polymer, [Cu(SO4)(CH5N3O)2]
n
, has been synthesized from aqueous solutions of CuSO4 and semicarbazide. In the crystal structure, the CuII atoms are chelated by two neutral semicarbazide molecules through the oxygen atom and a nitrogen atom of the amino group. The remaining two positions of the Jahn–Teller-distorted octahedral coordination sphere are occupied by oxygen atoms of two sulfate anions in the axial positions. The coordination bonds of the latter associate the polyhedra into polymeric chains running parallel to the c axis. There is a weak intramolecular hydrogen bond between the N—H group and an oxygen atom of the SO4
2– anion. Thirteen relatively weak intermolecular hydrogen-bonding interactions link the chains into a three-dimensional network. Hirshfeld surface analysis revealed that 64.7% of the intermolecular interactions are from O...H/H...O contacts and 20.1% from H...H contacts. Other interactions such as N...H/H...N or C...H/H...C contribute less to the crystal packing.