This volume contains the proceedings of the 5th Workshop on Formal Methods for Security (FMS) held in Tunis, Tunisia, June 23, 2014 as satellite event of Petri Nets 2014. FMS is dedicated to the advancement of the theory and practice of formal methods for security. We received 9 submissions. These submissions went through a rigorous review process; each submission was reviewed by at least 3 Program Committee members. The Program Committee members have selected 5 papers for publication. In addition to the five selected papers, two more papers were selected for an informal presentation at the workshop. We also have the chance to welcome one invited talk by Mark Ryan « Du-Vote: Remote Electronic Voting with Untrusted Computers » (joint work with Gurchetan Grewal, Michael Clarkson, Liqun Chen). We hope you will enjoy the FMS 2014 edition!