A new Co(II) coordination complex with the formula [Co(IS)2(H2O)4] (I), where HIS = isoquinoline-5-sulfonic acid, has been synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy, elemental analysis, fluorescence and surface photovoltage spectroscopy (SPS). X-ray diffraction analyses indicated that center Co2+ ion adopts six-coordinated with a N2O4 donors set of the two IS− and four aqua ligands, resulting in an ideal octahedral. Topological analysis on complex I considering {Co(IS)2(H2O)4} as nodes and hydrogen bonds as linkers gives a uninodal ten-connected net bct with point symbol (312 × 428 × 55). In the crystal packing, the components interact with pairs of intermolecular O-H...O hydrogen bonds and π-π stacks forming a 3D supramolecular network. The SPS of I indicates that there are positive response bands in the range of 300–600 nm showing photo-electric conversion properties. The solidstate photoluminescence property of I has also been investigated.