In this study, the thermoelectric properties of AgPbmSbTem+2 (LAST-m, m = 12, 16, 18, 20, 22, and 26), including the Seebeck coefficient, the electrical resistivity, and the thermal conductivity, were studied in the temperature range from 323 to 773 K. The Seebeck coefficient and the electrical resistivity exhibited the behavior of a degenerate semiconductor. The measured results of the carrier concentration supported the conclusions of the electrical transport properties. The lowest electrical resistivity and the thermal conductivity were observed, which leads to the best thermoelectric performance in LAST-18 and the dimensionless figure of merit ZT value of 0.8 at 773 K. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3138803]