An oxygen generator includes a composition for generating oxygen and at least one tuner compact having a core shell structure and including a compound selected from a peroxide decomposition catalyst, an acidic compound or a basic compound. The composition for generating oxygen having an oxygen source, an ionic liquid, a peroxide decomposition catalyst and, if the ionic liquid is an acidic liquid, a basic compound. The oxygen source is a peroxide compound. The ionic liquid is in the liquid state at least in a temperature range from −10° C. to +50° C. The peroxide decomposition catalyst is a metal oxide compound and/or a metal salt. There is also described a method for tuning the oxygen production rate of a composition for generating oxygen, and a device for generating oxygen in a tuned manner.