Mononuclear copper(II) terephthalate-pyridine, which has a regular one-dimensional structure, occludes large amounts of gases. The maximum amount of N-2 gas that can be occluded by mononuclear copper(II) terephthalate-pyridine is 1.1 mole per mole of copper(II) salt, indicating the presence of a large number of micropores. A porous structure, which is formed by hydrogen bonding and self-assembly of the linear copper(II) terephthalate-pyridine, was determined by X-ray crystallography.