(57) Liquid explosives comprising nitric acid and, as a fuel, one or more of nitromethane, nitroethane, nitropropane, nitrobenzene, nitrotoluene, dinitrobenzene and dinitrotoluene, are stabilised by the inclusion therein of at least 0.1% by weight of ammonium ions. The ammonium ions preferably are added in the form of an ammonium salt, which constitutes less than 35 weight percent of the explosive composition. An explosive composition which has been stabilised by the addition of ammonium ions can be de-stabilised by the addition of more nitric acid and/or fuel.