The transport properties of Ge50-xSbyTe100+x-y Alloys where 0 <= x <= 15 and 0 <= y <= 30 in the thin films state were studied. The temperature dependence of the d.c. electrical conductivity measurements for all prepared composition with different thickness, shows that, all samples behaves as a semiconductor up to a specific temperature at which an abrupt transition appears. That transition is due to the change of the semiconductor from non-degenerate to degenerate state. The temperature dependence of a.c. electrical conductivity measurements shows that, the a.c. conductivity for all films are frequency independent in the tested frequency range from 0.12 to 10 kHz. Thermoelectric power was found to have positive sign indicating that these alloys are p-type semiconductors. The value of temperature coefficient gamma was found to be in the order of 10(-4) stop (eV/K). The calculation of the free-charge carrier concentration and charge mobility shows that, the abrupt transition appears in thermoelectric power and conductivity are due to an abrupt increase in the mobility. (c) 2006 Springer Science+ Business Media, Inc.