This book constitutes the proceedings of the 20th International Colloquium on Theoretical Aspects of Computing, ICTAC 2023, which took place in Lima, Peru, during December 4-8, 2023.

The 20 full papers presented in this volume together with 3 invited papers and 1 tool paper were carefully reviewed and selected from 40 submissions.

They were organised in the topical sections as follows: Bring Together Practitioners; Researchers from Academia; Industry; Government to Present R ...