Atmospheric pressure plasma jet (APPJ) are nowadays used to promote the adhesion of composite materials, such as polymer/rubber or polymer/metal hybrid structures. Such materials are the key of success for the new developments in the industrial sector of transportation, e.g. the replacement of metals parts by polymers lead to weight savings for vehicles and therefore to reduction of fuel consumption [1]. APPJs are very attractive for industrial in-line treatments because no vacuum is required, and the very short treatment times are compatible with the line speed of manufacturing industry. Moreover, since plasma jets are produced inside specific devices, their properties are usually not or weakly affected by the distance between the source and the substrate, which is a requirement to treat 3D objects with complex shapes (fig.1). In this work, we will present different results and discuss on the role of plasma treatments and the induced surface modification of substrates to promote adhesion between different composite materials [1] S.T. Amancio-Filho, J.F. dos Santos, Polym. Eng. Sci. (2009), 1461-1476 [2] WO2013178538A1, H. Decorps, D. Doisneau, E-A. Filiol, J. Pulpytel, X. Callies, F. Arefi-Khonsari, L. Henao, O. Carton, (2013)