UV-spectroscopy method is used to study the influence ofdifferent varying growth parameters (growth rate, crystallization temperature, pH of the solution, complexating additions) on the absorption spectra of KH2PO4 crystals. It is found that the minimal value of the absorption coefficient (k ˜ 0.01–0.02cm−1)may be achieved under the following growth conditions: 1) crystallization temperature ˜ 55°C, 2) growth rate ˜ 1mm/24hrs, 3)pH = 4.