A method for preparing a redox flow battery electrolyte is provided. In some embodiments, the method includes the processing of raw materials containing sources of chromium ions in a high oxidation state. In some embodiments, a solution of the raw materials in an acidic aqueous solution is subjected to a reducing process to reduce the chromium in a high oxide state to an aqueous electrolyte containing chromium (III) ions. In some embodiments, the reducing process is electrochemical process. In some embodiments, the reducing process is addition of an inorganic reductant. In some embodiments, the reducing process is addition of an organic reductant. In some embodiments, the inorganic reductant or the organic reductant includes iron powder.