This book constitutes the proceedings of the 23rd International Conference on Formal Methods for Industrial Critical Systems, FMICS 2018, held in Maynooth, Ireland, in September 2018. The 9 regular papers presented in this volume were carefully reviewed and selected from 17 submissions. The book also contains two invited talks in full-paper length. In addition, there are 8 invited contributions in honor of Susanne Graf (Director of Research at VERIMAG Grenoble, France) on the occasion of her 60th birthday. The aim of the FMICS conference series is to provide a forum for researchers who are interested in the development and application of formal methods in industry. In particular, FMICS brings together scientists and engineers who are active in the area of formal methods and interested in exchanging their experiences in the industrial usage of these methods. The FMICS conference series also strives to promote research and development for the improvement of formal methods and tools for industrial applications.