This book constitutes the proceedings of the 33rd European MPI Users' Group Meeting, EuroMPI 2026, held in Vienna, Austria, during October 7–9, 2026.

The 12 full papers included in this book were carefully reviewed and selected from 17 submissions. They cover a broad spectrum of topics, including extensions to the MPI standard, communication algorithms, runtime systems, programming models and libraries built on MPI, interfaces to other parallel programming systems, performance optimization for emerging architectures and networks, correctness and verification
techniques, and tools supporting the development of scalable parallel applications.