Deuterated potassium dihydrogen phosphate (DKDP) crystals were grown under constant temperature and supersaturation by the solution circulating method. Temperature uniformity and appropriate mass transfer could be easier to achieve in comparison with other crystallization systems, because the overall volume of the employed two-vessel-four-zone crystallizer was significantly reduced. Optical transmission, Raman and infrared spectra, thermal diffusivities and laser damage thresholds of both potassium dihydrogen phosphate (KDP) and DKDP crystals were measured and compared with reference data. The excellent optical properties of the DKDP crystals obtained had demonstrated that the new crystallizer design is useful for growing large DKDP crystals of good quality and with greatly reduced heavy-water consumption. (c) 2006 Elsevier B.V. All rights reserved.