Aromatic polycarboxylate linkers provide structural rigidity and strong interactions among the metal centre and the carboxylate O atoms. A new three-dimensional coordination polymer namely, catena-poly[potassium [tetraaqua(μ-5-sulfobenzene-1,3-dicarboxylato)zinc(II)]], {K[Zn(CHOS)(HO)]} or {K[Zn(SIP)(HO)]}, where SIP is 5-sulfobenzene-1,3-dicarboxylate or 5-sulfoisophthalate, was obtained and characterized by elemental analysis and IR vibrational spectroscopy, and the single-crystal structure was determined by X-ray diffraction analysis. The compound crystallizes in the monoclinic space group P2/n with Z = 4. Topological analysis revealed that K-O interactions form a two-dimensional network, which is uninodal 4-connected and can be described with a point symbol (4.6), and this plane network is classified as sql/Shubnikov. The layers are connected by Zn ions coordinated to the SIP linker, forming a three-dimensional network. This net is a trinodal (3,5,6)-connected system with point symbol (3.4.5.6.7.8).(3.4.5.6.7).(3.7).