An extreme temperature decontamination composition such as a solution for destroying microorganisms, chemical warfare and bioterrorism agents is utilized that generally does not freeze at low temperatures down to about minus 25° F. and also has no significant evaporation or decomposition at temperatures up to about 120° F. The solution is effective against nerve agents and vesicants such as VX and HD, and various biological agents. The composition comprises a metallic salt of dichloroisocyanuric acid or dibromoisocyanuric acid, an aqueous solvent system comprising polar compounds such as water and an alkyl glycol, and a quasi hydrophilic compound. The composition can be formulated as a one part system wherein all components are blended together.