The microbial free single crystals of alpha and gamma glycine were grown from gel at room temperature in a new chemical route. These crystals showed a superior quality than the solution grown crystals. The metastable alpha-form and the stable gamma-form of glycine were crystallized in silica gel by solubility reduction method. The form of crystallization is confirmed by single crystal and powder X-ray diffraction analyses. The crystals of alpha and gamma glycine were found to crystallize in monoclinic and hexagonal crystal systems, respectively. For analyzing the functional group and thermal stability of alpha and gamma glycine crystals, spectroscopic and thermal analyses have been carried out. The dielectric studies were performed to find the dielectric constant of the grown crystals and the results are discussed. Second harmonic generation efficiency of the crystal was measured by Kurtz's powder method using Nd:YAG laser and it was found to be 2.68 times that of potassium dihydrogen phosphate crystals. (C) 2010 Elsevier B.V. All rights reserved.