CuInS2 single crystals were grown by a traveling heater method, which is one of the solution growth techniques. The temperature dependence of the X-ray diffraction of CuInS2 was determined between 10 and 300 K. The lattice constant of the a-axis decreased and that of the c-axis increased with increasing temperature. The linear thermal expansion of the c-axis calculated from the lattice constants decreased from 10 to 100 K. (C) 2011 The Japan Society of Applied Physics