This book constitutes the refereed proceedings of the First International Conference on Design of Cyber-Secure Critical Infrastructure, DCS-CI 2026, held in Buford, GA, USA, during September 2-3, 2026.

The 9 full papers presented in this volume were carefully reviewed and selected from 30 submissions. Also, it contains 3 papers from DCS-Water 2025.

DCS-CI (Design of Cyber-Secure Critical Infrastructure) is a joint academic-industrial forum that brings together researchers from academia, industry practitioners, and policymakers to discuss recent advances in securing and strengthening the resilience of critical infrastructure systems across energy, water, transportation, and other sectors. The DCS-CI series has its origins in the DCS-Water conferences started in 2024, which focused specifically on the cybersecurity challenges facing water and wastewater utilities.