Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to characterize the interface between thin molecular film (metal-free phthalocyanine, H2Pc) and top deposited gold layer. Such inorganic-on-organic interface is widely employed in molecular electronics and considered in numerous studies on contact phenomena in phthalocyanine-based devices. Analysis of ToF-SIMS data during the depth profiling and comparison of two different methods used for deposition of top metal layer (thermal evaporation vs. magnetron sputtering) reveal peculiar structural features of this interface. In particular, oxidation of molecules near the interface is accompanied by the mutual diffusion of components when Au layer is deposited by thermal evaporation. This diffusion leads to the saturation of metallic layer with organic species and hence to its vertical expansion. Both geometry and chemistry of Au/H2Pc interface can be modified by varying the deposition method. (C) 2009 Elsevier B. V. All rights reserved. `