Explosion suppression is now a well established means of mitigation against the consequences of a gas or dust explosion in industrial processing. Such systems were first deployed by Graviner Ltd (Maisey, H.R. Chem. Process Eng., March 1959) in the early 1950s following development of the technology for military purposes. The first industrial explosion suppression systems used proprietary halons as the explosion suppressant. By the mid-1970s, dry chemical power suppressants were becoming established as the preferred suppressant because of their superior suppression performance. Today water and halon suppressants are only deployed where they offer specific benefits over the dry chemical powders. The Montreal Protocol (UNEP, Sept. 1987 amended 1991 & 1992) has imposed controls on the availability of most halons-a production ban came into effect in the UK on 1 January 1994-because these agents have a proven ozone-depleting effect in the upper atmosphere. Not surprisingly, the chemical industry has identified a range of alternative agents that are environmentally friendly and have fire-extinguishing properties. Some of these agents are now being assessed as options for explosion suppression. This paper considers the demand on an explosion suppressant and contrasts the effectiveness of available suppressant agents against industrial explosions.