Reactions of pyridine-2,6-dicarboxylic acid(H2PDA) with cobalt(Ⅱ) acetate resul-ted in two cobalt(Ⅱ) complexes,[Co(HPDA)2].2H2O.0.5CH3OH(1) and [Co2(PDA)2(H2O)5].2H2O(2),which were characterized by single-crystal X-ray diffraction,IR and electronic absorption spectra.For both complexes,every cobalt atom lies in peudo-octahedral coordination geometry,and the whole structures present 3D frameworks linked by π-π stacking interactions and extensive hydrogen bonds.Magnetic studies showed λ =-83.38 cm-1 for(1) and g = 2.50 and J =-1.38 cm-1 for(2).