PCM-16 is a phosphine coordination material comprised of Dy(III) and triphenylphosphine oxide, which displays the highest reported CO2 BET surface area for a Ln(III) coordination polymer of 1511 m(2) g(-1). PCM-16 also adsorbs 2.7 wt % H-2 and 65.1 wt % O-2 at 77 K and 0.97 bar. The adsorption-desorption behavior of a series of organic vapors has been studied in PCM-16 to probe the nature of certain host-guest interactions in the pores. Aromatic and polar guest species showed high uptakes and marked adsorption/desorption hysteresis, while aliphatic vapors were less easily adsorbed. The surface area of PCM-16 could be increased significantly (to 1814 m(2) g(-1)) via exchange of Me2NH2+ cations in the pores with smaller NH4+ groups.