Single crystals of the quaternary phase AgCd2GaSe4 were grown using the method of directed crystallization. Their physical properties were studied. Studying the temperature dependence of electrical conductivity an impurity defect band with activation energy of similar to 0.30 eV in the upper half of the energy band gap was identified. Based on the analysis of the spectral dependence of the absorption coefficient, the width of the energy gap of the crystals was estimated similar to 1.7 eV at T=293 K. At the edge of the intrinsic absorption band this dependence could be approximated by the Urbach rule with the characteristic disorder parameter Delta(0)similar to 0.079 eV. Based on this value, concentration of the point defects responsible for the absorption edge blurring was determined to be similar to 1.4 x 10(20) cm(-3). (C) 2011 Elsevier B.V. All rights reserved.