Ion beams of 200 keV Na-23(+) at a fluence of 1 X 10(17) cm(-2) were implanted at 77 K into Ni/Si bilayer couples. The Ni and Si concentration profiles were measured via Rutherford backscattering spectrometry (RBS), and the Na-23 and H-1 profiles via resonant nuclear reaction analysis (RNRA). Migration of sodium, radiation-induced and thc thermal silicide formation, and hydrogen decoration were investigated upon thermal treatment up to 930 K. The results on Na migration are compared with those obtained after Na implantation in metals, silicon and Ni/SiO2 bilayers.