The acid dyes of the formula (I) of the invention can be prepared, for example, by reacting the reactive dye of the formula (III) in which M and n are as already defined and X1, X2 and X3 are a halogen atom, preferably a chlorine or bromine atom, with one or more???e.g., 1, 2 or 3compounds of the formulae (IV), (V), (VI) and/or (VII) The reactions are normally conducted in an aqueous medium at a p