The title complex, [Sr(C(12)H(8)N(2))(2)(H(2)O)(4)](C(2)N(10)), contains an [Sr(phen)(2)(H(2)O)(4)](2+) cation (phen is 1,10-phenanthroline) and a 5,5'-diazenediylditetra-zolide anion (site symmetry 2). The Sr(2+) cation (site symmetry 2) is coordinated by four N atoms from two chelating phen and four water mol-ecules. In the crystal structure, the water mol-ecules and the N atoms in the tetra-zolide rings form an extensive range of O-H⋯N hydrogen bonds which link the complex into a two-dimensional structure. An adjacent layer further yields a three-dimensional supramolecular network by offset face-to-face π-π stacking inter-actions of the phen ligands [with centroid-centroid distances of 3.915 (2) and 4.012 (2) Å]. The two bridging N atoms of the anion are equally disordered about the twofold rotation axis.