Two 3rd generation steels were studied: an austenitic-ferritic MnAl steel and an austenitic-martensitic quenched and partitioned (Q&P) steel. Hydrogen absorption during elaboration was simulated by exposing the steels to deuterium atmosphere during their final thermal treatment. Nitrogen-exposed specimens were also deuterium cathodically charged in order to simulate hydrogen entry in the steels during an optional electrogalvanization process. Thermal desorption mass spectrometry (TDS), combined with aging at room temperature and cold rolling, was used to study diffusion and trapping. The evolution of different TDS spectral contributions with aging and cold rolling allowed educated guesses on their origin. Peaks specific to martensitic transformation were identified.