A new organic-inorganic complex [FeII(Phen)3]L 2-2H2O (Phen = 1,10-phenanthroline, L = 2-mercaptonicotinic acid) was synthesized and characterized. The crystal structure of the complex was determined by single-crystal X-ray diffraction, crystallizing in orthorhombic crystal system, space group Pba2 with the unit cell parameters a = 13.4711(11), b = 17.0021(14), c = 11.7026(9) Å, and Z = 2. The Fe(II) atom wa s six-coordinated with N(1), N(1A), N(2), N(2A), N(3), and N(3A) from three Phen ligands and formed a slightly distorted octahedral geometry. The base units form a one-dimensional chain via π-π-stacking interaction between 2-mercaptonicotinic acid fragments. A new 3D layered compound was obtained through hydrogen bonding. © Pleiades Publishing, Ltd., 2010.