Seven compositions were prepared in the system As2Te3‐Tl2Te‐As2Se3. Some of the samples were amorphous while others were diphasal including both amorphous and crystalline phases. The electrical and thermal properties of the samples were structure dependent. At room temperature the resistivity values ranged from 4.7×10−3to 1.8×105&OHgr;‐cm, Seebeck coefficient values were 40 to 1210 &mgr;V/°K and thermal conductivity values were 18.1 to 2.2 mW/cm‐deg.