We stabilized the high voltage (HV) excited CO2 laser to the center of the gain curves using a photoacoustic effect generated from the laser itself. A commercial condenser microphone is located in the plasma free region. This detects pressure waves occurring in the plasma free region when laser radiation is absorbed. The signal from the microphone is used to control a feedback circuit to stabilize the frequency and power of the laser radiation. The frequency stability is estimated to be better then 3X10-8.