A microporous metal-organic framework 1 Co(NDC)(4,4'-Bipy)(0.5).G(x), (NDC = 2,6-naphthaleriedicarboxylate; 4,4'-Bipy = 4,4'-bipyridine; G = guest molecules) was synthesized and structurally characterized of a doubly interpenetrated primitive cubic net. To make use of the framework flexibility, 1 was activated at temperatures of 150 and 200 degrees C to form 1a and 1b, respectively, exhibiting highly selective sorption behaviors of hydrogen over nitrogen-gas molecules.