A device (36, 100, 200) for measurement of concentration of an oxidizable gas is disclosed, which comprises a catalyst (102) inside a housing (101, 201). The catalyst is surrounded by insulation (105) inside the housing. The device (100, 200) further comprises at least two thermometers, one of which is located at the inlet of the device, and one being located inside the catalyst (102). The device also has means for calculating a concentration based on the temperature measurements. A sterilization chamber and a filling machine having a device according to the main claim are also disclosed.
