This book constitutes the thoroughly refereed post-workshop proceedings of the 24 th International Workshop on Securit Protocols, held in Brno, Czech Republic, in April 2016. The 13 thoroughly revised papers presented together with the respective transcripts of discussions have been carefully reviewed. The theme of the workshop was Evolving Security - considering that security protocols evolve with their changing requirements, their changing mechanisms and attackers' changing agendas and capabilities.