This book constitutes the refereed proceedings of the 9th International Conference on Reversible Computation, RC 2017, held in Kolkata, India, in July 2017. The 13 full and 5 short papers included in this volume together with one invited paper were carefully reviewed and selected from 47 submissions. The papers are organized in the following topical sections: foundations; reversible circuit synthesis; reversible circuit optimization; testing and fault tolerance; and quantum circuits.