In the title compound, [Co(C12H12O4)(C5H5N)2] n , the Co(II) cation is coordinated by four O atoms from three 5-tert-butyl-benzene-1,3-di-carboxyl-ate anions and two N atoms from pyridine mol-ecules in a distorted octa-hedral geometry. One carboxyl-ate group of the anionic ligand chelates a Co(II) cation while another carboxyl-ate group bridges two Co(II) cations, resulting in a polymeric layer parallel to (101). Weak C-H⋯O hydrogen bonds occur between adjacent polymeric layers. In the crystal, one of pyridine mol-ecules is equally disordered over two positions.