Restoration of thermal images distorted by the atmosphere is presented. The method is based upon atmospheric modulation transfer function (MTF) analysis, both theoretical and experimental. Thermal infrared (IR) atmospheric MTF measurements carried out simultaneously in both atmospheric IR windows (3 - 5 and 8 - 12 μm wavelengths) are presented too. The MTFs were evaluated via point spread function (PSF) measurements, under various meteorological conditions and different signal to noise ratios (SNRs). Results are analyzed and shown to be in very good agreement with theoretical predictions.