The CCIS book constitutes selected papers of the 12th International Conference on Computational Science and Computational Intelligence, CSCI 2025, which took place in Las Vegas, NV, USA, during December 3–5, 2025.

A total of 43 papers was carefully reviewed and selected for inclusion in this book from the following tracks: 4 papers from 142 submissions to the Research Track on Parallel & Distributed Computing, CSCI-RTPD; 20 papers from 154 submissions to the Research Track on Computational Science, CSCI-RTCS; 9 papers from 58 submissions to the Research Track on Internet of Things & Internet of Everything, CSCI-RTOT; and 10 papers from 120 submissions to the Research Track on Computational Biology, CSCI-RTCB.

The papers were organized in topical sections as follows: Parallel & Distributed Computing and Applications; Computational Science - Theories, Algorithms, and Applications; Internet of Things and Applications; Computational Biology; and Poster Papers.