A new series of dinuclear ruthenium(II,II) dicarboxylates, but not dinuclear ruthenium(II,III) dicarboxylates, have been prepared. Dinuclear ruthenium(II,II) dicarboxylates, which have a regular two- or three-dimensional network structure, occlude large amounts of gas. The maximum amount of N-2 gas that can be occluded by these complexes is 1.0-1.7 moles per mole of ruthenium atoms, indicating the presence of a large number of micropores. These complexes exhibited pore volume-dependent catalytic activity for the hydrogenation of ethylene.