Hydrogen peroxide is vaporized (20) and mixed (30) with ammonia gas in a ratio between 1:1 and 1:0.0001. The peroxide and ammonia vapor mixture are conveyed to a treatment area (10) to neutralize V-type, H-type, or G-type chemical agents, pathogens, biotoxins, spores, prions, and the like. The ammonia provides the primary deactivating agent for G-type agents with the peroxide acting as an accelerator. The peroxide acts as the primary agent for deactivating V-type and H-type agents, pathogens, biotoxins, spores, and prions. The ammonia acts as an accelerator in at least some of these peroxide deactivation reactions.