  This paper reports on experimental measurements of the gas temperature in a
dielectric barrier discharge reactor powered by a high voltage pulsed signal.
It is shown that the thermal behavior of the reactor follows a first order
model. However, an unexpected runaway phenomenon was observed at a frequency of
300Hz. A sudden increase in the power source and consequently in reactor
temperature which reaches 170{\deg}C is observed. This behavior is discussed in
terms of input power variation with temperature, possibly due to a resonance
phenomenon.
