<p>Inorganic–organic hybrids based on polyoxometalates (POMs) have been regarded as promising materials for preparation of capacitors and electrochemical sensors, due to excellent redox property of POMs and structural stability during undergoing reversible multi−electron transfer process. For developing POM–based hybrids with energy storage and electrochemical properties, herein, two copper compounds based on octamolybdates, [Cu(HBBIP)₂][β − Mo₈O₂₆] (<b>1</b>) and [Cu(BBIP)₂][β − Mo₈O₂₆]_0.5·3H₂O (<b>2</b>), were isolated under hydrothermal conditions by using 1, 3 − bis(1 − benzimidazolyl) propane (BBIP) as a flexible bis(benzimidazole) ligand. Both <b>1</b> and <b>2</b> showed supramolecular structures. In <b>1</b>, the aggregation between [β − Mo₈O₂₆]⁴⁻ and Cu(II) ions leaded to a POM−based inorganic chain, and the monodentate ligand HBBIP coordinated with Cu(II) ion on the chain via Cu − N bonds. But the BBIP ligands represent bidentate linkers, coordinating with Cu(II) ions to forming a two–dimensional grid–like layer in <b>2</b>. The [β − Mo₈O₂₆]⁴⁻ anions are sandwiched between two layers through hydrogen bond interactions. The BBIP ligands exhibited different configurations due to the flexibility of the linker. Compounds <b>1</b> and <b>2</b> as electrode materials showed enhanced capacitive performances with specific capacitances of 1446&#xa0;F g^–1 for <b>1</b>, 1152&#xa0;F g^–1 for <b>2</b> at a current density of 1&#xa0;A g^–1, as well as good cycling stability after 5000 cycles. Furthermore, two compounds exhibited remarkable electrocatalytic activities for the reduction of bromate and sensing ability.</p>