The hydration of 1-butene (B), cis-2-butene (C) and trans-2-butene (T) to 2-butanol (A) catalysed by a strong acid ion-exchange resin (XE-307) was studied in the temperature range of 75–150°C. Kinetic experiments were performed by passing aqueous solutions of these butenes or 2-butanol through a resin bed (particle size 0.6–0.7 mm) of known capacity at a constant flow rate. Besides hydration, isomerization of the three butenes takes place. The experimental results can be explained by assuming that all reactions proceed via the sec-butyl carbenium ion as reactive intermediate. The reactions involved are equilibrium reactions. Numerical values of the rate constants of the various reactions and the equilibrium constants have been determined. The overall equilibrium constant of the hydration reaction of the butenes in the liquid phase is considerably less favourable than in the corresponding hydration of propene. The rate constants for butene hydration are of a similar order of magnitude to those for propene hydration. When resin particles of 0.65 mm diameter are used, the rate of reaction is found to be affected by intraparticle diffusion limitations at temperatures above 115°C.