Dyeing process using a sequestrating agent

In a process for the dyeing of textile fibers in an aqueous dyeing bath containing a metal-containing dyestuff sensitive to demetallization by a sequestrating agent at a temperature and for a period sufficient to transfer said dyestuff to said textile fibers, wherein said bath contains at least one sequestrable metal in the form of a metal of said dyestuff, an alkaline-earth metal or a heavy-metal impurity, the improvement which comprises introducing into said bath a sequestrating agent in the form of a hydroxy-(C.sub.1 to C.sub.4)-alkane phosphonic acid salt capable of sequestrating said impurity without affecting the physical-chemical characteristics of said dyestuff, said salt being selected from the group which consists of the sodium, potassium and lithium salts of hydroxyethane-1,1-di-phosphonic acid and 1-hydroxypropane-1,1,3-triphosphonic acid.