The rates of some reactions are greatly limited by diffusion rates of paramagnetic gases. ne idea to enhance them by means of applying a magnetic field was considered and tested in this paper. The introduction of a weak magnetic field into the oxidation reaction of aqueous suspensions of ferrous hydroxide increased the reaction rate to a considerable extent, which was attributed to magnetically induced convection for the existence of a gradient of susceptibilities and magnetic strength. The idea can be valuable in all the processes, in which diffusion rates of the paramagnetic gases control the reaction rates or at least play an important role.