This paper is an appraisal of the application of optical-mechanical-scanners operating in the non-photographic infrared wavelengths (3-5 and 8-14 micrometres) to mineral exploration in Australia. Pundamental principles of the operation of airborne scanners and their data output, thermal infrared (IR) imagery, are summarized. It is contended that thermal IR imagery often depicts the distribution of electromagnetic radiation emitted from earth surface materials better than aerial photographic techniques because optical-mechanical-scanners sample wavebands which straddle the wavelength peak of earth surface emission. To illustrate the geological features which such scanners can depict, reference is made to thermal IR imagery of a number of areas in Australia where the technique has been applied for exploration purposes. The images demonstrate that this technique can detect structural features like faults and folds, stratigraphic data by distinguishing different rock types and delineating their