Carbon fiber, being black (high absorptivity) material, is difficult to analyze by the conventional infrared (IR) techniques. Probably due to this fact, most of the studies reported in literature have been restricted to the thermal degradation of polyacrylonitrile-based fibers only. In the present work, we have used a recently developed mirage-FTIR technique for recording the IR spectra of carbon fibre at different stages of production, right from the precursor to final product. A study of microstructural/chemical changes occuring not only provides the information on structure but also demonstrates an unusual and highly technical industrial application.