This work addresses an off-shore oscillating water column for producing electricity from sea waves. It describes the modelling of this device and the study of control techniques that could improve energy extraction. Optimisation techniques applied improved the device performance for a wide number of sea states. A control strategy was developed with the objective of improving the quality of the energy absorbed by the device. This proved to be effective. In a later stage of this work, some experiments considering a variable pitch Wells turbine were performed with the objective of applying phase and amplitude control: it was proved that it is possible to obtain a resonant response to a sinusoidal wave with a frequency different from the device's natural frequency. (C) 2010 Elsevier Ltd. All rights reserved.