Single crystals of AgCd2GaS4 have been created by melting technique and single crystal growth using AgGaS2 as a solvent. Real defect structure of stoichiometric crystals has been studied by transmission electron microscopy. Chemical composition variations and optical transparency range lambda = 0.63-13 mu m have been measured for a AgCd2GaS4 single crystal with dimensions of 40 mm in length and 9 mm in diameter. (c) 2006 Elsevier B.V. All rights reserved.