We present a study on the interfacial behavior of TM/Si and TM/SiO2 systems (TM: Mo, NiTi) by electron-induced X-ray emission spectroscopy (EXES), X-ray photoelectron spectroscopy assisted by argon bombardment and secondary ion mass spectrometry (SIMS). A few nanometers thick amorphous interlayer forms without annealing at the interface of each system. We give an estimation of the composition of the interlayers, and of the spatial disposition of the compounds formed along the interfacial zone. We find a good agreement and complementarity between the analysis methods. Studied TM/SiO2 systems are shown to be more reactive than TM/Si systems. Moreover, the deposition rate of the metal could influence the reactivity between the metal and the substrate. (C) 2003 Elsevier Science B.V. All rights reserved.