A new chelating agent diethylenctriaminepentaacetic acid (DTPA) is employed for the first time to investigate its effect on the metastable zone width, crystal growth and characterization of DAST single crystals. The width of DAST in methanol is measured with and without adding DTPA and EDTA. The presence of DTPA in the DAST solutions enhances the metastable zone width as compared to the EDTA added solutions. The pure and the chelating agents added DAST crystals are grown by the slow cooling method and their crystal size distributions are presented. The addition of the chelating agent DTPA significantly suppresses spurious nucleation and cluster formation in the DAST solution, so that fewer, but larger crystals are easily obtained. The crystalline powder of the grown crystals is examined by X-ray diffraction. The Fourier transform infrared (FTIR) and UV-vis-NIR spectroscopic analyses have been done for the DAST samples. The hardness of the grown pure, DTPA and EDTA added DAST crystals is measured on the (001) face under different loads. (c) 2006 Elsevier B.V. All rights reserved.