ABSTRACT: Methane gas and coal dust are an ever-present source of risk during underground coal mining operation. Methane gas and coal dust can create a combustible atmosphere. Adding a high enough energy source might ignite this combustible atmosphere and lead to an explosion. The prevention of methane gas and coal dust accumulation during mechanised cutting and crushing has evolved to an extent that might be accepted as a state of safe mining. Historic events suggest that methane gas ignitions can occur despite a general preventative practise being in place. Active explosion barriers are considered a last resort once methane gas and/or coal dust explosions occur. Initially these barriers were developed to protect the continuous miner operator from those methane gas and coal dust ignitions occurring at the coal cutting face. The possibility of an explosion mitigation control being flexible enough to react independent of the scale of the explosion, sparked the evolution of the active explosion barrier technology. Over twenty years of continuous research and development, operational experience and numerous success stories, resulted in a technology being adaptable to different types of coal mining operations such as longwall and room and pillar operations. This paper reviews this evolution of the active explosion barrier technology from early prototypes to modern mobile barrier modules that are readily deployed as a safety control system. The paper furthermore outlines the requirements and techniques that influence the function of these barriers.