The PPOSS project (Planetary Protection of Outer Solar System) is an initiative supported by the European Commission under the Horizon 2020 programme. PPOSS focuses on planetary protection of outer solar bodies, in particular icy moons, and tackles scientific, technological and policy-making challenges raised by this topic. This intensive three year programme will provide an international platform and forum where science, industry and policy actors will meet to nurture and catalyse discussions, exchange of knowledge and produce policy recommendations on the matter of planetary protection. Space exploration missions are international endeavours and planetary protection is by nature an issue of global relevance. Thus, the PPOSS project will promote international cooperation bringing partners and observers from non-European countries.