The present project aims at innovating the dyeing process for leather, supplanting commercial acid dyes with biodegradable naturalised products. The goal is to improve the safety profile of the business for environmental compatibility and the eco-sustainability of leather goods manufacturing to pursue cost-effective strategies. Specifically, the project will target the achievement of: _ Reliable synthetic processes for dyes from the lab-scale to the kilo-lab scale. _ Consistent dye penetration into leather, to obtain colour homogeneity. _ Tailored formulations of different colorants, to achieve the dyeing based on the concept of “trichromy”. _ Efficient dyeing bath exhaustion. _ No chemical additives in bath wastewaters, coming from the synthesis of the dye. _ High aesthetical profile of the dyed leathers, as for touch and fullness. _ Fastness and physical tests to assess leather quality. _ Finishing protocols to improve the quality of the dyed leather. _ Compliance with UNI – 10594 and 10826 requirements and with guidelines for “not harmful” classification contained in directive 2002/231/EC. _ Biodegradability of dyeing effluents, using E. coli bacteria.