Cu(Ga1-xInx)(y)S-z alloys have been grown by the temperature difference method under a controlled S vapor pressure. The crystal structures of Cu(Ga1-xInx)(y)S-z alloys, whose alloy compositions are located on the the line from CuGaS2 to (Ga,In)(2)S-3, are found to be classified into three types: chalcopyrite, defect chalcopyrite and hexagonal structures. The CuGa1-xInxS2 alloys were grown from Cu-excess solution and the crystal structure was chalcopyrite. The variations of lattice parameters with alloy compositions in the Cu(Ga1-xInx)(y)S-z and CuGa1-xInxS2 crystals have been characterized. (C) 2002 Elsevier Science B.V. All rights reserved.