The development of new products without adequate boundary conditions is risky and difficult. All real life operating conditions must be well known for their design and validation. The paper presents the process chain for deriving realistic boundary conditions and developing new products for H2 fuel cells using the example of a flat membrane humidifier, as well as describing the necessary validation environment. For new components development, the requirements at MAHLE were derived from both, customer data as well as from internal tests on a fuel cell system, and merged. A system from partner Ballard was investigated in detail with the original BoP parts. New components such as electric high-voltage coolant pumps, cathode modules for air conditioning, humidification and water separation as well as filters for intake air and hydrogen were developed from the requirements derived. Validation was carried out on several test benches with different integration levels. The new humidifier design was verified and further developed in several iteration loops by using a functional test bench. After passing through several product cycles, endurance tests were carried out to identify degeneration effects or other weak points. In parallel, functional humidifier verification as part of a cathode module in an environment that replaced the H2 fuel cell with an emulator was carried out. Finally, the complete module was validated in the target system so the full function can be proven.