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A series of isostructural metal−organic framework polymers of composition [Cu₂(L)(H₂O)₂] (L= tetracarboxylate ligands), denoted NOTT-nnn, has been synthesized and characterized. Single crystal X-ray structures confirm the complexes to contain binuclear Cu(II) paddlewheel nodes each bridged by four carboxylate centers to give a NbO-type network of 6⁴·8² topology. These complexes are activated by solvent exchange with acetone coupled to heating cycles under vacuum to afford the desolvated porous materials NOTT-100 to NOTT-109. These incorporate a vacant coordination site at each Cu(II) center and have large pore volumes that contribute to the observed high H₂ adsorption. Indeed, NOTT-103 at 77 K and 60 bar shows a very high total H₂ adsorption of 77.8 mg g⁻¹ equivalent to 7.78 wt% [wt% = (weight of adsorbed H₂)/(weight of host material)] or 7.22 wt% [wt% = 100(weight of adsorbed H₂)/(weight …