An aqueous stabilised chlorine dioxide solution for use as a universal biocide. The stabilized solution preferably, but not necessarily, includes: (A) an effective stabilising amount of ClO2− ions； (B) an effective biocidal amount of ClO2； (C) an acidulator sufficient to release ClO2, in a safe manner, and (D) an amount of water qs. The solution may, but not necessarily, have a molar ratio of components (A):(B) that is from 20:1 to 1:20.
