Combustion experiments in air have been performed using TG/DTA analysis, which served for ignition temperature and kinetics data determination. Fly-ash carbon was treated with carbonates and hydroxides. The ignition temperature dependence on alkali metal salt concentration was investigated. Results showed that the ignition temperature decreased for treated samples. The activation energy of impregnated samples decreased. Qualitative comparison of modified and original samples showed that higher heat of combustion was achieved for impregnated samples.