This book constitutes the proceedings of the 24th International Conference on Implementation and Application of Automata, CIAA 2019, held in  Kosice, Slovakia, in July 2019. The 17 regular papers  presented together with 2  invited papers  in this book were carefully reviewed and selected from 29 initial submissions. The topics of the papers include complexity of languages and language operations, regular expressions, picture languages, jumping automata, input driven and two-dimensional automata, tree languages and tree transducers, architecture of oritatami systems, intruder deduction problem, context sensitive ash codes, rational relations, and algorithms for manipulating sequence binary decision diagrams