A method based on the complex effect of a field on semiconducting electrodes under potentiodynamic conditions and measurements of the magnetoresistance effect has been used to study the mobility of the free charge carriers mu m in a thin germanium electrode. The measurements carried out in 0. 1 N Na//2SO//4 on electrodes made from almost natural germanium demonstrated the bell-shaped course of the variation of mu m both as a function of the electrode potential E and as a function of the surface potential V//s with a maximum corresponding to the state of flat bands (V//s equals 0) and zero charge in the space-charge region on the surface of the semiconductor (Q//s//c equals 0).