A new crystalline complex of pyridine 3-carboxylic acid (nicotinic acid) - with manganese has been successfully grown in sodium meta silicate gel and its structure has been determined by single crystal X ray diffraction technique. The complex crystallises in space group P2(1)/c, with cell dimensions a=8.727(5)Å, b=10.182(5)Å, c=7.138(5)Å and β=100.005(5)°. The carboxylate group bridges two central metal atoms, leading to a 3D polymeric frame work of the complex. The crystal structure is stabilized by intermolecular hydrogen bonds. FT-IR spectral studies were used to identify the functional groups and the bonding sites of the ligand with the metal atoms. The elemental analysis confirmed the stoichiometry of the complex. The thermo-gravimetric analysis and differential thermal analysis were carried out to evaluate the thermal properties and stability of the grown crystal. The kinetic and thermodynamic parameters were also calculated. © 2011 Elsevier B.V. All rights reserved.