In the field of spintronics, there are many reasons to use molecular tunnel barriers in devices such as low cost, flexibility and long spin life time in organic materials [1, 2]. What happens at the interfaces in these organic-inorganic hybrid systems is so relevant to the properties that a word has been proposed for it: spinterface [3]. The discrete nature of the molecular levels explains the variation of the magneto-transport properties with respect to the type of molecules and the nature of the interfaces [4]. To investigate such spinterface issues there is a need for very well-defined interfaces, which can be obtained in ultra-high vacuum conditions (UHV). The aim of this work is to realize model hybrid hetero-structures with a molecular monolayer as tunnel barrier between two ferromagnetic layers (spin valve). Modifying the way molecules are linked to the substrate, the crystallographic orientation of the substrate and the nature of the molecules are possible ways to modify the system spinterfaces. In this study, the grafting under UHV of the molecular layer (1-hexadecanethiol molecules, noted C16MT) on epitaxial ferromagnetic Fe (001) electrodes has been studied using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). To avoid the formation of pinholes during deposition of the Co ferromagnetic top electrode of the spin-valve, an original soft-landing technique has been used, based on the condensation at low temperature of a Xe layer on the self-assembled monolayer before metal deposition. The electrical homogeneity of the obtained junctions has been controlled from the micro to the nanoscale by Ballistic Electron Emission Microscopy (BEEM) [5]. Investigation of the magnetotransport properties of these model spin- valves is in progress and will be confronted to the precise analysis of the system bottom spinterface by spin-resolved IPES (Inverse PhotoEmission Spectroscopy). References: [1] J. R. Petta, S. K. Slater, et al., Physical Review Letters, 93, 136601, 2004. [2] S. Sanvito, Chemical Society Reviews, 40, 3336-3355, 2011. [3] S. Sanvito, Natur Physics, 6, 562-564, 2010. [4] M. Galbiati, S. Tatay, et al., Applied Physics Letters, 106, 082408, 2015. [5] A. Junay, S. Guézo, et al., Journal of Applied Physics, 118, 085310, 2015.