RICAP-16 will be the sixth edition of the RICAP Conference. The Conference, entirely dedicated to the study of high-energy cosmic rays, has been traditionally organized by the INFN sections and Physics Departments of the three public Universities of Roma ( University “La Sapienza”, University Roma “Tor Vergata” and University “Roma Tre”). The 2016 edition will be held in Villa Tuscolana, Frascati, Roma Scientific Topics The aim of the Conference will be to present and discuss some of the most relevant theoretical and experimental results in the field of high-energy cosmic rays (gamma, neutrinos, charged cosmic rays). Special attention will be paid to the multi-messenger search for high-energy cosmic rays sources, including gravitational wave searches. A special session will be dedicated to Dark Matter search. The Conference will give the opportunity to collect experimental results from presently operating experiments. Experiments in progress and future projects will be discussed, debating on the different features and on sensitivities. Particular relevance will be given to the discussion of the open questions in high energy Astroparticle Physics.