Thallium monosulfide single crystal was prepared and characterized by x–ray diffraction. The electrical measurements in the temperature range form 100 to 360 K, show that σ⊥= 8.9 x 10–7 (Ω.cm)–1 when the current flow direction makes right angle to the cleavage plane of the crystals, and σ // = 1.39 x 10–7 (Ω.cm)–1 when the current flows is parallel to the cleavage plane. The width of the band gap was calculated from the electrical data and found to be Eg = 1.1eV. The anisotropy of the electrical conductivity (σ⊥/σ//) was also studied in this work. The photosensitivity was calculated for different levels of illumination which showed that the recombination process in TIS single crystals is monomolecular