A microporous coordination polymer, namely, [Co3(ina)4(OH)(C2H5OH)3](NO3)·C2H5OH·(H2O)3 (1, or MCF-38, ina = isonicotinate), with 8-connected {Co3(OH)} clusters as the structural secondary building units, has been solvothermally synthesized. The hydroxo-centered Co(II) cluster involves multiple active metal sites. The interesting apical ligand substitutions have been directly observed, and the corresponding products of [Co3(ina)4(OH)(G)x(H2O)n](NO3)·G·(H2O)m (1 PrOH, G = PrOH, x = 2, n = 1, m = 3; 1 BuOH, G = BuOH, x = 2, n = 1, m = 1, and 1 MeOH, G = MeOH, x = 3, n = 0, m = 7) have also been obtained by solvothermal syntheses or crystal-to-crystal transformations. High-pressure H2 adsorption measurement at 77 K reveals that activated 1 can absorb 2.2 wt % H2 at 5 bar. The relative H2 absorption at low pressure (86% of the storage capacity at 1 bar) is higher than the corresponding values reported for some typical porous coordination polymers. The magnetic studies of 1 show a dominant antiferromagnetic coupling between Co(II) ions of intra- and inter-cluster. [ABSTRACT FROM AUTHOR]