In this work, the Cu(II)/Cu(I) redox couple is studied as an alternative half-cell electrolyte for Redox Flow Battery (RFB) applications. Copper is an abundant and environmentally friendly material that, in combination with appropriate complexing agents, can be solubilized at high concentrations in aqueous media. The effect of adding chlorides as complexing agents in different concentrations, as well as the effects of temperature, have been examined with the objective of increasing the chemical stability of copper chloro-complexes in solution as well as to improve upon the reversibility of these electrochemical reactions. Also, an important shift in potential towards more positive values has been observed when high concentrations of chlorides are used, deviating approximately 0.5 V from the standard redox potential of this couple. This allows for the application of this copper redox couple as a positive electrolyte for RFB technologies.