We investigate high-quality Na-doped Cu2ZnSnS4 (CZTS) single crystals grown by using the traveling heater method and the effect of Na doping on the fundamental properties of these crystals. Na-doped CZTS single crystals were obtained from Sn solution at growth temperatures of 850-900 degrees C and at speeds of 4 mm/day. The crystals have a kesterite structure, as determined by powder X-ray diffraction and Raman measurements. The Hall effect properties such as hole concentration, conductivity, and hole mobility are enhanced with increasing Na concentration. These results reveal that Na improves the electrical properties of CZTS. (C) 2016 Elsevier B.V. All rights reserved.