Atmospheric pressure plasmas have many advantages for widespread applications since that are no necessary to use vacuum equipments. The work presented here is preliminary experimental results of hydrogen oxidation using an atmospheric pressure plasma. The experiment was done by a mixture gas included with a small amount of hydrogen and oxygen in an argon or a nitrogen plasma. As a result of mass spectrometry measurement, it has been found that hydrogen gas could be oxidized by the atmospheric pressure plasma. Moreover, dependence of the hydrogen conversion rate on the input power for discharge was confirmed. It has been also found that the hydrogen conversion rate in nitrogen plasma is higher than in argon one.