A process for producing an additive for hydrocarbon fuels by combining picric acid, powdered iron, an activating acid, and a liquid organic solvent. Alternatively, the powdered iron can first be washed with the activating acid and the rinsed with water or alcohol or water followed by alcohol; subsequently the washed and rinsed iron is combined with the picric acid and the liquid organic solvent. In the case of either alternative, hydroquinone can be added to the mixture in order to control undesired oxidation and corrosion, thereby further enhancing the stability of the additive.