[en] Purpose: To provide a gaseous waste recombiner having reduced size and excellent H₂ removing performance for use in BWR type power plants. Constitution: A metal catalyst having a high hydrogen removing performance at high temperature and low pressure loss prepared by appending an alumina layer on a cellular Ni-Cr alloy support and supporting a noble metal such as Pt on the alumina layer is combined with a catalyst having a high hydrogen removing performance even at a low temperature prepared by disposing an alumina layer on a mesh-like stainless steel support and supporting Pd thereon, which are filled in a recombiner for H₂ and O₂ in gaseous wastes containing H₂ and O₂ separated from reactor water. This enables to provide a small and safety recombiner having a high performance even at low H₂ density ypon start-up and shutdown of a nuclear power plant and capable of efficiently removing H₂ even at high H₂ density during reactor operation. (Seki, T.)