The time of flight secondary ion mass spectroscopy (ToF-SIMS) technique was employed to investigate the interaction of liquid lead-bismuth eutectic (LBE) atoms with the surface and subsurface of a T91 steel taking into account the contribution of plastic deformation. It is shown that both Pb and Bi can penetrate the steel network only in plastically deformed material. No microstructural interface (lath boundaries, grain boundaries...) was found to be preferential site for trapping Pb and Bi but clustering with molybdenum has been identified. Pb seems to be easier adsorbed than Bi because of its higher affinity with oxygen.