A process for preparing a biocidal composition comprising the steps of: (i) dissolving at least one polyol in water to form a water/polyol co-solvent solution； (ii) adding at least one organic acid to the water/polyol co-solvent solution； (iii) adding at least one stabiliser to the water/polyol co-solvent solution； (iv) adding a flavonoid composition comprising at least one flavonoid selected from the group consisting of: poncirin, neoeriocitrin, isonaringin,rhoiflin, naringen, neodiosmin, hesperidin, neohesperidin and naringenin.A non-microbial non-toxic biocidal composition having a pH in the range of 1 to 2.9, comprising at least one water soluble flavonoid compound, at least one organic acid, at least one polyol, at least one stabilizer, and water.
