This book constitutes the proceedings of the 16th International Conference on Information Systems Security, ICISS 2020, held in Jammu, India, during December 16-20, 2020. The 11 regular papers, 2 short papers and 3 work-in-progress papers included in this volume were carefully reviewed and selected from a total of 53 submissions. The papers were organized in topical sections named: access control; AI/ML in security; privacy and Web security; cryptography; and systems security.