Abstract The adsorption—desorption phenomena of alcohols were studied by measuring differential capacity—time curves in a flowing solution. The alcohols investigated were methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol and 1-octanol. The differential capacity—time curves for these alcohols show different shapes with and without peaks. These curves are explained qualitatively. The curves were used to study the adsorption reversibility of the alcohols at a mercury electrode. The adsorption of methanol is irreversible and that of ethanol is almost irreversible. Some of the adsorbed molecules of 1-propanol are desorbed. The adsorption of 1-butanol is almost reversible, and the adsorption of 1-pentanol, 1-hexanol, 1-heptanol and 1-octanol is reversible.