Derivatives of β-K 2Bi 8Se 13 are an interesting series of materials for thermoelectric investigations due to their very low thermal conductivity and highly anisotropic electrical properties. Up to now substitutions on the Bi and alkali metal sites have been studied in order to tune the thermoelectric properties. In this work, the thermoelectric properties of the sulfursubstituted K 2Bi 8Se 13-xS x (0<x<13) are presented with respect to Seebeck coefficient, the electrical and thermal conductivity as a function of temperature. Seebeck coefficient measurements showed the n-type character of all members while electrical conductivity shows higher values compare to the other solid solution series of the same type. The lattice thermal i conductivity is affected due to the Se/S disorder. The temperature dependence of the figure-of-| merit ZT shows that these materials have potential for high temperatures applications with promising thermoelectric performance.