Self-assembly of dipotassium salt of piperazine-1,4-bis(2-ethanesulfonic acid) (K(2)pesp) with AgNO3 in H2O/DMF gave rise to a novel three-dimensional sulphonate silver(l) complex, [Ag-2(mu(2)-OH2)(pesp)](n) (1). Each silver(I) ion is coordinated by one nitrogen and two oxygen atoms from three pesp ligands and one oxygen atom from coordinated water molecule in a distorted tetrahedral geometry.