Abstract: A biocidal solution is provided having a pH of from 5 to 7 and an available free chlorine content of from 500 to 1,000 ppm. A method is also provided for producing the biocidal solution in an electrolytic cell or cells having anode and cathode chambers which produce respective anolyte and catholyte solutions, wherein the biocidal activity of the biocidal solution is conferred on the solution primarily in the anode chamber. The method includes the steps of supplying the cell or cells with a solution having a salt concentration of 2.0 to 5.0 g/L, such that the solution passes through the anode chamber at a flow rate per anode surface area of 1.25×103 to 2.75×103 L hr−1m−2, and applying current to the cell or cells sufficient to produce a biocidal solution having the above free chlorine content and pH.