The present invention relates to the additive for solid fuel combustion processes (coal, biomass) that both improves fuel efficiency, reduces fuel consumption, and has the ability to prevent sludge formation in combustion chamber and reduce pollutant emission, ensuring stable and highly efficient furnace operation even when using bad-quality fuel. The additive includes the activator component with high polarity; the active component capable of generating active sites; the auxiliary component capable of promoting the generation of active centers; the stabilizing component able to regulate the physicochemical properties and helping to create a stable additive according to the ratio of components (% mass) as follows: Activator component: 20-30 Active component: 50-60 Auxiliary component: 5-9 Stabilizing component: 1-5, and Solvent: suitable In addition, the invention also relates to the production process for this additive.