An analysis of existing air independent propulsion system solutions shows that fuel cells have the potential to achieve the greatest energy efficiency and silencing actions resulting from direct conversion of energy during a chemical reaction without moving parts. This paper describes research intended to identify noise generated by a fuel cell demonstrator and the first phase of work related to its silencing. During these investigations main noise sources were determined, while sound propagation and sound insulation of the fuel cell enclosure were performed in accordance with the civilian and military standardization guidelines.