Energeticism, also called energism or energetics  (), is a superseded theory in science that posits that energy is the ultimate element of physical reality. Energeticism was developed during the end of the 19th century by the chemist Wilhelm Ostwald and mathematician Georg Helm. It was also promoted by physicist Ernst Mach, though his full commitment to it was sometimes ambiguous. Energetiscism attempted to substitute the hypothesis of atoms and molecules by energy relations.
Ludwig Boltzmann and Max Planck constantly rebutted the idea of energeticism in favor of atomic theory. The program of energeticism faded away in the 20th century with the confirmation of the existence of atoms.