Adopting Baym-Barrera-Pethick method and using the temperature-depende
nt anomalous spectrum of bulk liquid He-4, we have evaluated the phono
n-limited mobility of the positive ions in bulk liquid He-4. The mobil
ity of the positive ions has the temperature variation of T-4 With ext
ra temperature dependent terms for phonon-limited scattering region. T
he results of our theory are in excellent agreement with the experimen
tal results.