An ultrasonic method is used to study the onset of ion transport inlithium oxides in a ceramic of the Li-Si-Ge-As-S-O system. The onset temperature for ion transport estimated from the temperature dependence of the relative change in the propagation speed of ultrasound is the same as that obtained by other methods, which indicates that the ultrasonic method is applicable to studies of the onset of ion conductivity inlithium oxide semiconductors.