A 3D porous metal-organic framework generating 1D channels, [Mn(NDC)(DEF)](n) (1), has been prepared from the solvothermal reaction of Mn-II and 2,6-naphthalenedicarboxylic acid (H2NDC) in diethylformamide (DEF). When DEF molecules coordinating MnII, which occupy the channels, are removed from 1 by heating the crystal of 1 at 250 degrees C under vacuum for 18 h, structural change occurs as evidenced by X-ray powder diffraction patterns. Desolvated solid [Mn(NDC)](n) (2), which contains coordinatively unsaturated MnII sites, reveals remarkable sorption capabilities for N-2, H-2, CO2, and CH4 gases and exhibits type I sorption behavior indicative of permanent microporosity.