The present invention discloses an activated biocidal aqueous solution containing hydrogen peroxide (activated peroxide solution) obtainable by subjecting an initial solution of hydrogen peroxide in water to a non-thermal electrical discharge process, such as a glow discharge plasma or a corona discharge. The resulting activated peroxide solution containing 0.05 to 20% (w/w) hydrogen peroxide has a pH in the range of 2 to 4, an oxidation-reduction potential (ORP) in the range of 400 to 600 mV, and the solution when having a peroxide content in the range of 0.05% to 0.5% (w/w) has a conductivity in the range of 100 to 500 μSiemens/cm, the solution when having a peroxide content in the range of 0.1% to 5% (w/w) has a conductivity in the range of 100 to 450 μSiemens/cm, and the solution when having a peroxide content in the range of 5% to 20% (w/w) has a conductivity in the range of 100 to 350 μSiemens/cm. The pH, ORP and conductivity are measurable under conditions essentially without the presence of additional compounds in the solution. The biocidal activity of the solution is substantially higher than that of a common peroxide solution. The biocidal solution may be used for any purpose where disinfecting and/or sanitizing and/or cleaning and/or bleaching and/or preservative activity is required. The present invention further discloses a non-thermal electrical discharge process, in particular a pulsed corona induced low frequency pulsed DC plasma discharge process, for the preparation of the activated peroxide solution.