The　asymmetric　unit　of　the　title　coordination　polymer,　[Co(C9H4N2O4)(C2H4N4)(n)　or　[Co(L-1)(L-2)](n)　consists　of　one　crystallographically　independent　Co2+　centre,　one　L-1(2-)　ligand　and　one　L-2　ligand　(L-1　=　1H-benzimidazole-5,6-dicarboxylic　acid,　L-2　=　3-amino-1,2,4-triazole).　The　Co2+　centre　is　coordinated　by　two　carboxylato-O　atoms　from　two　independent　L-1(2-)　ligands　and　two　nitrogen　atoms　from　L-2　and　another　L-1　ligand.　Thus,　the　metal　center　adopts　a　four-coordinate　mode,　forming　a　tetrahedral　geometry.　Interestingly,　through　the　combination　of　two　L-1(2-),　two　L-2　ligands　and　two　Co2+　ions,　a　basic　repeating　unit　is　constructed,　resulting　in　the　formation　of　a　one-dimensional　straight　chain　structure.　These　chains　are　further　expanded　to　the　final　three-dimensional　framework　via　N-H　center　dot　center　dot　center　dot　O　hydrogen-bonding　interactions.