He carried out research in the areas of kinetic theory of gases, electrical conductivity, gas discharges, he radiation, ferromagnetism and photochemistry.
Among his students were James Franck (Nobel prize for physics 1925), Eduard Grüneisen, Robert Pohl, Erich Regener and Hans von Euler-Chelpin (Nobel prize for chemistry 1929).
He was the father of Otto Heinrich Warburg.