Abstract Large single crystals of ReS 2 and ReSe 2 crystallizing in a layer-type structure (space group P 1 ) have been grown by chemical vapour transport in a temperature gradient of 1 to 5K cm -1 at about 1080°C. The triclinic symmetry and lattice parameters have been checked by X-ray diffraction measurements. The electrical properties were investigated. For the first time, the temperature dependence of the resistivity and Hall voltage is reported for n- and p-type ReS 2 and ReSe 2. N-type samples had a room- temperature resistivity of about 2 and 5 ohm · cm. The Hall mobility of 22 and 16 cm 2 V · s at 300K varied with temperature as T -1.1 and T -2.4, respectively. The activation energy for the carriers of n-type ReS 2 and ReSe 2 as a function of the temperature was 40 and 240 meV, respectively. In the case of the p-type crystals, the doping with phosphorus was strongly compensated.