This four-volume set constitutes the refereed proceedings of the Second World Conference on Explainable Artificial Intelligence, x AI 2024, held in Valletta, Malta, during July 17-19, 2024. The 95 full papers presented were carefully reviewed and selected from 204 submissions. The conference papers are organized in topical sections on:Part I – intrinsically interpretable XAI and concept-based global explainability; generative explainable AI and verifiability; notion, metrics, evaluation and benchmarking for XAI.Part II – XAI for graphs and computer vision; logic, reasoning, and rule-based explainable AI; model-agnostic and statistical methods for e Xplainable AI.Part III – counterfactual explanations and causality for e Xplainable AI; fairness, trust, privacy, security, accountability and actionability in e Xplainable AI.Part IV – explainable AI in healthcare and computational neuroscience; explainable AI for improved human-computer interaction and software engineering for explainability; applications of explainable artificial intelligence.