The thermal diffusivity of a polycrystalline-sintered sample of Ag 2 Te was measured from room temperature to about 900K. The thermal conductivity was evaluated from the thermal diffusivity, heat capacity and density. The value at room temperature is 0.93Wm −1 K −1 . Using the data of the electrical resistivity and Seebeck coefficient obtained in a previous study, the dimensionless figure of merit ZT of α- and β-Ag 2 Te was evaluated. The ZT value of α-Ag 2 Te is higher than that of β-Ag 2 Te. The maximum value of ZT is 0.27 at 370K obtained in the α-phase.