The invention described herein provides a matrix-based ion source including a gas heating device for providing heated gas at a defined temperature to the ionization region of the ion source. The ion source may also include a temperature sensor. The heating device and temperature sensor may be operably connected to work as a closed feedback loop to provide gas at a constant, pre-determined, temperature to the ionization region. Also disclosed is a mass spectrometer system having the matrix-based ion source. A method of producing ions employing gas that is heated to a pre-determined temperature is also provided.