Potassium nitrate reacts with different fuels to release energy through exothermic reactions. This experiment tested nine fuel mixtures—magnesium, aluminum, charcoal, sulfur, wood shavings, zinc, copper, iron, and sugar—combined with potassium nitrate to determine which produced the fastest and most intense reaction. Reactivity was measured by the time required for each reaction to complete using slow-motion video analysis. Magnesium and sulfur showed the strongest reactivity, completing reactions in about five seconds, while charcoal and copper produced slower, less intense reactions. These results supported the hypothesis that magnesium powder mixed with potassium nitrate would be the most reactive combination due to its highly exothermic nature. Overall, the findings demonstrate how fuel composition influences reaction speed and intensity, offering insights relevant to pyrotechnics and energy production where controlled reactivity is essential.