Abstract: A storage-stable aqueous concentrate for the preparation of a disinfectant and a disinfectant obtainable from such a concentrate by dilution are disclosed. The concentrate comprises hydrogen peroxide, colloidal silver, a biopolymeric stabilizer such as gum arabic, and phosphoric acid. In order to improve long-term stability and to reduce initial decomposition of the hydrogen peroxide in the first few days after preparing the concentrate, the concentrate further comprises sodium nitrate or sodium sulfate. The concentrate is free of any synthetic organic complexing agents, thus rendering the concentrate suitable for food- and drinking water applications. Also disclosed are methods of preparing and using the concentrate.