A process for the simultaneous tanning and dyeing of collagen containing fibrous material, wherein the said material is treated with a liquor containing at least one reactive dyestuff selected from the group of formula (1) and (2) ##STR00001## wherein A.sub.1, A.sub.2 and A.sub.3 are each independently of the others the radical of a monoazo, polyazo, metal-complexed azo, anthraquinone, phthalocyanine, formazan or dioxazine chromophore having at least one sulfo group, B is an organic bridge member, Q.sub.1, Q.sub.2, Q.sub.3 and Q.sub.4 are each independently of the others hydrogen or unsubstituted or substituted C.sub.1-C.sub.4alkyl, G.sub.1 and G.sub.2 are halogen, 3-carboxypyridin-1-yl or 3-carbamoylpyridin-1-yl, (Z.sub.1).sub.2-3 is 2 to 3 identical or different fiber reactive radicals, Z.sub.2 and Z.sub.3 are each independently of the other identical or different fiber reactive radicals, and b is the number 0 or 1, by combining two steps of leather production, tanning and dyeing, into a single step, thus, preserving resources and reducing the environmental impact.

A process for the simultaneous tanning and dyeing of collagen containing fibrous material, wherein the said material is treated with a liquor containing at least one reactive dyestuff selected from the group of formula (1) and (2) ##STR00001## wherein A.sub.1, A.sub.2 and A.sub.3 are each independently of the others the radical of a monoazo, polyazo, metal-complexed azo, anthraquinone, phthalocyanine, formazan or dioxazine chromophore having at least one sulfo group, B is an organic bridge member, Q.sub.1, Q.sub.2, Q.sub.3 and Q.sub.4 are each independently of the others hydrogen or unsubstituted or substituted C.sub.1-C.sub.4alkyl, G.sub.1 and G.sub.2 are halogen, 3-carboxypyridin-1-yl or 3-carbamoylpyridin-1-yl, (Z.sub.1).sub.2-3 is 2 to 3 identical or different fiber reactive radicals, Z.sub.2 and Z.sub.3 are each independently of the other identical or different fiber reactive radicals, and b is the number 0 or 1, by combining two steps of leather production, tanning and dyeing, into a single step, thus, preserving resources and reducing the environmental impact.