This book constitutes the proceedings of the 45th International Conference on Application and Theory of Petri Nets and Concurrency, PETRI NETS 2024, held in Geneva, Switzerland, during June 26-28, 2024.  The 19 full papers and 2 invited papers included in this book were carefully reviewed and selected from 42 submissions. They were organized in topical sections as follows: Business Process Modelling and Mining, Semantics and Complexity, Reachability, Verification and Model Checking, Applications and Tools.