Abstract: In the reaction contrivance disclosed which serves the purpose of oxidizing hydrocarbons over a catalyst, with the catalyst being disposed in a casing of the contrivance. Next to an inlet into a reactor disposed in the casing, is a mixing chamber fitted rigidly, and linked with the casing of the contrivance. A separator is arranged at the outlet of the reactor. The mixing chamber provides a means of forming a reaction mixture of the reactants and the catalyst drawn from the casing and into the reactor. By virtue of this arrangement the entire surface of catalyst is in contact with the reactants and the yield of final product increases.