Deep Reinforcement Learning (DRL) has emerged as a powerful paradigm for enabling autonomous decision-making in complex and dynamic environments. However, the ‘black-box’ nature of deep neural networks often hinders the transparency and interpretability of DRL agents, posing significant challenges for their adoption in safety critical applications. This chapter introduces the field of Explainable Deep Reinforcement Learning (XRL), a critical area of research focused on developing methods to understand, interpret, and trust the decisions made by DRL agents. We provide a comprehensive overview of XRL, covering fundamental concepts, a review of the current literature, and a detailed examination of a proposed methodology. We demonstrate the application of XRL in the context of the classic LunarLander-v3 control problem, showcasing how techniques like SHAP (SHapley Additive exPlanations) can provide valuable insights into the agent’s decision-making process. The chapter presents a thorough analysis of simulation results, including training performance, feature importance, and comparative evaluations, to highlight the benefits of integrating explainability into DRL systems. We conclude with a discussion of the broader implications of XRL and future research directions for developing more transparent, robust, and trustworthy autonomous systems.