The observation of acoustoelectric current saturation and domain propagation inn‐type InP single crystals is reported. The electromechanical coupling constantKand the dominant acoustic frequencyfare obtained from the variation of the incubation time for current decay with applied drift field.K2= 1.0×10−3andf= 17 GHz. The enhancement of acoustic gain in a transverse magnetic field is examined and compared to the predictions of the microscopic theory. Semiquantitative agreement can be obtained by assuming a slight scan of the dominant accoustic frequency with magnetic field.