Large quantities of explosive hydrogen-oxygen mixtures can be produced by leaks or accidents in technical plants, e.g. nuclear reactors. The invention relates to a catalyst, a catalyst system, an arrangement for recombining hydrogen with oxygen, and a method for producing a catalyst. The inventive catalyst is characterized in that the ignition point of the mixture is exceeded under no circumstances even though the catalyst works in a strictly passive manner without outside intervention and the recombination is an exothermal reaction. The basic idea is to design the catalyst such that the catalyst autonomously limits the activity thereof in accordance with the prevailing temperature.