Two methods for the measurement of the drift velocity of ions in liquids are described in detail. Both the dc voltage applied across the drift length, and the time or delays involved in the methods can be measured with an accuracy better than 0.1%. Moreover the time of flight is deduced with good accuracy from an extrapolation of a linear plot of the ionic current as a function of time. As a result, drift velocity or mobility measurements with an accuracy of 1% or better can be made. Drift velocities from 0.1 up to 3000 cm/sec, in electric fields up to 25 000 V/cm, can be measured.