This book constitutes the refereed proceedings of the 16th International Conference on Network and System Security, NSS 2022, held in Denarau Island, Fiji, on December 9-12, 2022. The 23 full and 18 short papers presented in this book were carefully reviewed and selected from 83 submissions. They focus on theoretical and practical aspects of network and system security, such as authentication, access control, availability, integrity, privacy, confidentiality, dependability and sustainability of computer networks and systems.