This book constitutes the proceedings of the 20th International Conference on Hybrid Artificial Intelligence Systems, HAIS 2025, held in Salamanca, Spain, during October 16-17, 2025.

The 53 full papers included in this book were carefully reviewed and selected from 120 submissions. They focus on the following topical sections:

Part I: Agricultural and Environmental Monitoring; Biomedical Applications; Cybersecurity and Network Protection; Data Mining and Decision Support Systems.

Part II: Deep Learning and Representation Learning; HAIS Energy Applications; Evolutionary Computation and Optimization; Reinforcement Learning and AI Planning; Smart Mobility and Transportation Optimization; Time Series and Forecasting Methods.