We have studied thermoelectric magneto- thermoelectric properties of Bi1-xSbx foils in semimetal and semiconductor states. The Bi1-xSbx foils were prepared by crystallization a thin layer of the melt on the inside polished of surface of a rapidly rotating copper cylinder. The cooling rate of the liquid phase was ~5*105 K/s [1]. The rapidly solidified foils have a microcrystalline structure and texture (1012) with thickness 15-40 mm.figureFig.1. Resistance and thermopower (inset) as a function of temperature for the Bi and Bi1-xSbx foils. 1- Bi, 2- Bi-3at%Sb, 3- Bi-9at%Sb, 4- Bi-15at%Sb. The thermoelectric figure of merit depending on the foils structure, magnetic field and entire temperature has been calculated. It is discussed the question the enhancement of the thermoelectric figure of merit in semiconductor Bi1-xSbx foils at high temperatures, using the reduction phonon-thermal conductivity, due to phonon – grain boundary scattering.