Diglycine zinc chloride, a semi-organic nonlinear optical crystal was grown by conventional slow evaporation and Sankaranarayanan-Ramasamy method. By employing this unidirectional method, diglycine zinc chloride single crystals of diameters 10, 30 and length up to 60 mm were grown. The growth conditions have been optimized. A maximum growth rate of 1.5 mm per day was realized. A comparative damage threshold analysis made on the diglycine zinc chloride crystals by conventional and unidirectional method shows that the crystal grown by Sankaranarayanan-Ramasamy method has higher damage threshold. The conventional and Sankaranarayanan-Ramasamy method grown diglycine zinc chloride crystals were also characterized by chemical etching, UV-vis analysis, dielectric constant, dielectric loss, Vicker's microhardness analysis and the results were compared. The present study indicates that the crystal quality of Sankaranarayanan-Ramasamy method grown diglycine zinc chloride is good compared to conventional slow evaporation method grown crystal. (C) 2009 Elsevier B.V. All rights reserved.