This course introduces the design and operation of commercial chemical reactors for multiphase in which at least two phases are contacted with each other. These phases can be gas, liquid or solid. . Multiphase reactors are common in the chemical industry, e.g. for oxidations, hydrogenations, desulfurization, denitrification, Fischer-Tropsch synthesis, biotechnological processes, waste water treatment. Classical and novel reactor types will be discussed.