The bis-μ-dicarboxylate molybdenum(II) complexes Mo(II) 2 L 2 (L = trans-O 2 C-CH=CH-CO 2 (1), p-O 2 C-C 6 H 4 -CO 2 (2), trans-trans-O 2 C-CH=CH-CH=CH-CO 2 (3), 2,5-O 2 C-C 5 H 3 N-CO 2 (4), and trans-O 2 C-C 6 H 1 0 -CO 2 (5)) were prepared and their gas-occlusion properties were characterized. The dinuclear complexes have quadruple Mo-Mo bonds, with the ground electronic configuration (σ) 2 (π) 4 (δ) 2 . All of these complexes are capable of occluding a large amount of gas (1 or 2 mol of N 2 gas per 1 mol of molybdenum atoms). Investigation of the structures of these complexes indicates that gases are most probably occluded in homogeneous and linear micropores which are composed of micropore units surrounded by four dicarboxylate bridges. 1 3 C-CP/MAS NMR measurements indicate that gas molecules are held in the micropores created by the dicarboxylate ligands.