Velocity distributions in a capillary have been measured using NMR mic
roimaging techniques, following application of pulsed electric fields
in a weak ionic solution. The closed system exhibits electroosmosis in
which the net fluid flow is zero. The time evolution of the electroos
motic flow profiles have been compared with the predictions of a theor
etical model based on a wall slip within the Debye layer and drag of t
he remaining fluid. Excellent agreement is found both for the velocity
distributions and for the time dependence of those distributions.