Abstract: The invention relates to a method and an apparatus for optimizing thermal treatment processes of fabrics, preferably textile fabrics, in tensioning, drying and setting machines. According to the invention, the apparatus for the thermal treatment of fabrics comprises individual sections, to which is conveyed heated air. The air leaves each section via outgoing air slits, which are provided with at least two measuring locations per section. The measuring locations enable determination of the difference of the outgoing air temperature of the sections. After determining the location of the dryness point by comparing the outgoing air temperatures with the predetermined temperature, the measuring point at which there exists no difference, or only a minimal difference, is determined. The characteristic point for reaching the predetermined temperature of the fabric is thus found which, together with the found maximum, determines the adjustability of the speed, the energy supply or the outgoing air temperature.