This study examines the performance of a Proton Exchange Membrane Electrolyzer powered by an off-shore Oscillating Water Column (OWC) with a focus on sustainability assessment through exergy analysis. The research indicates that the exergy efficiency of the electrolyzer is closely tied to the energy output of the OWC device, which is influenced by its design scale. The findings reveal that as the OWC size scale increases, the exergy efficiency of the electrolyzer and the overall renewability of the process decrease. Optimal results, including a maximum exergy efficiency of 60.59% and a maximum renewability index of 1.54, are achieved when the OWC diameter chamber is approximately equal to or less than 1m. Moreover, the study highlights that higher renewability index values and exergy efficiency are obtained with smaller OWC sizes, showcasing environmental favorability. The research also points out that the levelized cost of hydrogen production may be impacted by the size of the OWC. Overall, coupling the OWC with the PEM electrolyzer demonstrates an exergy efficiency range of 30-60% for the production of green hydrogen, emphasizing the potential of off-shore wave energy in sustainable hydrogen production.