The bis-mu-dicarboxylate ruthenium (II,III) complexes, Ru (II,III)(2)L2Br (L=trans-O2C-CH=CH-CO2 (1), trans-trans-O2C-CH=CH-CH=CH-CO2 (2), and p-O2C-C6H4-CO2 (3)), were prepared and their gas-occlusion properties were measured. The effective magnetic moments at room temperature are in the range 3.76 and 4.02 BM per dinuclear, consistent with the Values of Ru(II)-Ru(III) compounds. All these complexes are capable of occluding a large amount of gas. The maximum amounts of occluded nitrogen for 1-3 are 0.6, 0.9, and 1.4 moles per one mole of ruthenium atoms, respectively. These amounts are almost the same as those of the correspondent chloride complexes. This suggests that bromide complexes 1-3 would form a highly similar capillary structure to that of ruthenium (II,III) dicarboxylate bridged by chloride atoms.