Apparatus for isotope exchange reaction

An apparatus for isotopic exchange reaction, which comprises a plurality of units arranged in succession, each unit comprising a mist-forming means for forming water containing hydrogen isotopes into a mist of fine water particles containing hydrogen isotopes, said mist having a fine particle size of from 0.1 .mu.m to 50 .mu.m, a catalyst bed for promoting isotope exchange reaction between at least one of hydrogen gas and deuterium gas, and the hydrogen isotopes in the mist of fine water particles supplied in a mixed state from the mist-forming means, means for removing the mist from the gas passed through the catalyst bed, a first conduit leading the water containing hydrogen istopes to the mist-forming means, a second conduit for discharging the gas freed from the mist by the mist-removing means, and a third conduit for discharging the mist collected by the mist-removing means as a liquid containing hydrogen isotopes;

• the mist-forming means of a preceeding unit being connected to the second conduit of a succeeding unit and the third conduit of the preceeding unit being connected to the first conduit of the succeeding unit.