Multipurpose platforms are innovative solutions to combine the sustainable exploitation of multiple marineresources. Among them, hybrid wind-wave systems stand out due to the multiple synergies between these twoforms of marine renewable energy. The objective of this work is to develop a hybrid system for monopilesubstructures, which are currently the prevailing type of substructure for offshore wind turbines, and morespecifically to focus on the wave energy converter sub-system, which consists in an oscillating water column. Forthis purpose, an in-depth experimental campaign was carried out using a 1:40 scale model of the wave energyconverter sub-system and the monopile substructure, considering regular and irregular waves. Based on theexperimental results the performance of the device and its interaction with the wavefield were characterised–afundamental step to fully understand the benefits and limitations of this hybrid wind-wave system, which setsthe basis for its future development. Regarding the performance, the best efficiency was obtained with theturbine damping corresponding to a 0.5% orifice size, and two resonance peaks were identified (T= 9 and 6 s).As for the interaction of the hybrid system with the wavefield, between 5% and 66% of the incident wave poweris reflected and between 3% and 45%, transmitted. The wave period was found to be the parameter that mostinfluenced wave run-up on the substructure. This characterisation of the behaviour of the hybrid system showsthat it is indeed a promising option for further development.