Single crystals of TaS 3 and Nb-doped Ta 0.8 Nb 0.2 S 3 were grown by the usual vapor-transport method. The low-field DC resistivity, thermoelectric power, and I–V characteristics of both samples have been measured. Non-linear I–V characteristics due to possible CDW transition were found in Ta 0.8 Nb 0.2 S 3 at temperatures up to 400K and the temperature dependence of resistivity remained insulator-like even when the temperature was as high as 400K. Possible CDW transition in Ta 0.8 Nb 0.2 S 3 crystals at temperatures above 400K is suggested and need further studies to confirm.