The problem of drying of vegetable tanned sole leather is sharp, because of the presence of high quantities of water soluble matter and the great tendency for oxidation of tannins. During drying process water soluble substances are often extracted from the leather, reducing the quality of the product. On the other hand high temperatures cause oxidation of tannins, giving an undesirable dark brown colour, while drying in low temperature requires long time. The influence of drying process thus may be dramatic, both on quality of sole leather and on the production cost. In the proposed project, the application of a sole leather dryer will be studied equirref with a heat pump, instead of a simple exposure into the open air or vacuum drying used at present. The concrete objectives of the research will be: - to define the best values of relative humidity, temperature, air circulation etc. - to obtain sole leather of high quality - to reduce drying time - to avoid heavy costs due to defects from uncontrolled drying.