A 2D grid-like (4, 4)-connected topology coordination polymer, [Co(BTA) 2 (H 2 O) 2 ] n (1), where HBTA = 2-(1H-benzotriazol-1-yl)acetic acid, has been synthesized by hydrothermal method and characterized by single crystal X-ray diffraction, IR spectroscopy, elemental analysis and surface photovoltage spectroscopy (SPS). X-ray diffraction analyses indicated that 1 displays octahedral metal centers with secondary building units (SBUs) [Co(BTA) 2 (H 2 O) 2 ] bridged by the BTA − ligands. In the crystal, the 2D supramolecular architecture is further supported by O-H•••O, O-H•••N, C-H•••O hydrogen bonds and π•••π stacking interactions. The SPS of polymer 1 indicates that there are positive response bands in the range of 300-600 nm showing photo-electric conversion properties. There are good relationships between SPS and UV-Vis spectra.