The p-type Ag(Pb1-ySny)(m)SbTe2+m materials shown in the figure demonstrate promising thermoelectric properties that are controlled with the parameters y and m. They can reach a maximum figure of merit of similar to 1.45 at 630 K. This surpasses the figure of merit of the present state-of-the-art p-type materials such as TAGS (1.2) and PbTe (0.8) at comparable temperatures.