H-2 adsorption and syngas purification in charged soc metal-organic framework are investigated using atomistic simulations. As experimentally observed, the extraframework NO3- ions are entrapped in carcerand-like capsule with negligible mobility. At low pressure, H-2 adsorption occurs concurrently at multiple sites near the exposed indium atoms and organic components. The capsule is accessible at high pressure through the surrounding channels by restricted windows. Adsorption sites identified are remarkably consistent with inelastic neutron scattering measurements. The isotherm and isosteric heat of H-2 adsorption predicted match well with experimental data. As loading rises, the isosteric heat remains nearly constant, revealing the homogeneity of adsorption sites. CO2/H-2 selectivity in syngas adsorption is up to 600 and substantially higher than other nanoporous materials. With a trace of H2O, the selectivity increases slightly at low pressure due to promoted adsorption Of CO2 by H2O bound proximally to the exposed indium atoms, but decreases at high pressure as a consequence of competitive adsorption of H2O over CO2. (C) 2009 American Institute of Chemical Engineers AIChE J, 55: 2422-2432, 2009