While chlorine dioxide (ClO2 ) has chlorine in its name, chlorine dioxide’s chemistry is radically different than elemental chlorine. One atom makes all the difference. Chlorine dioxide is a high-value biocide that has excellent biocidal properties, higher oxidative capacity than chlorine, and proves effective over a wide pH range. Moreover, chlorine dioxide’s versatile, rapid kill mechanism usually results in the extra benefit of not having to add additional chemicals to address bacterial resistance.