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Two Co(II)-based coordination polymers: [Co 2 (L) 2 (bib) 2 ] n (1) and {[Co 2 (L) 2 (bimb) 2 ]·2H 2 O·DMA)} n (DMA = N,N-dimethylacetamide) (2) using 4,4′-bis(thiomethylene) dibenzoic acid (H 2 L) as the first ligand, 1,4-bis(imidazol)-butane (bib) and 1,4-bis(imidazol-1-ylmethyl)benzene) (bimb) as the second ligands, were synthesized under the condition of solvothermal and characterized by X-ray single-crystal diffraction, elemental analysis, IR spectra and thermogravimetric analysis (TGA). X-ray single-crystal diffraction analysis exhibits that 1 and 2 belong to the triclinic crystal system, space group P -1. The central Co(II) ions exhibit a regular spatial tetrahedral structure which are coordinated by two O atoms from two L2− ligands and two N atoms from two N-donor ligands. Furthermore, the photocatalytic degradation properties and mechanism of 1 and 2 for methylene blue (MB) were investigated. The results show that the band gap (E g) of 1 and 2 is 3.78 eV and 3.82 eV, and the equipotential point (pH pzc) of 1 is 4.25. Both 1 and 2 show excellent photocatalytic degradation for MB. •OH is the main active substance causing MB degradation. The photocatalytic degradation for MB of 1 and 2 is in line with the first order kinetics equation. The pH pzc of complex 1 is 4.25. When pH < 4.25, 1 has a positive charge on the surface, and will generate electrostatic repulsion with MBH2+, inhibiting the adsorption of 1 to MB, so the degradation rate of MB is greatly reduced. When pH > 4.25, complex 1 has a negative charge on the surface and generates electrostatic attraction with MBH2+, which promotes the adsorption of 1 to MB, so the degradation rate of MB is greatly increased. Image 1 [ABSTRACT FROM AUTHOR]