The book constitutes the joint refereed proceedings of the 10th International Conference on Relational Methods in Computer Science, RelMiCS 2008, and the 5th International Workshop on Applications of Kleene Algebras, AKA 2008, held in Manchester, UK in April 2008. The 26 revised full papers presented together with 2 invited papers were carefully reviewed and selected from numerous submissions. The papers describe the calculus of relations and similar algebraic formalisms as methodological and conceptual tools with special focus on formal methods for software engineering, logics of programs...