Double copper formazan reactive dyes of the formula ##STR1## in which R.sup.1 is hydrogen, hydroxylsulfonyl or chlorine; R.sup.2 is hydrogen or hydroxylsulfonyl; one of two radicals R.sup.3 and R.sup.4 is hydrogen and the other is hydroxylsulfonyl; Q is fluorine or chlorine; and X is a radical of the formula ##STR2## where R.sup.5 and R.sup.6 are identical or different and each is independently of the other hydrogen or unsubstituted or cyano- or hydroxyl-substituted C.sub.1 -C.sub.4 -alkyl and Y is hydroxyl or the radical NR.sup.7 R.sup.8 where R.sup.7 and R.sup.8 are identical or different and each is independently of the other hydrogen or unsubstituted or cyano-, hydroxyl- or hydroxylsulfonyl-substituted C.sub.1 -C.sub.4 -alkyl, with the proviso that R.sup.5 and R.sup.6 are not both hydrogen, or salts thereof are useful for dyeing and printing hydroxyl- or nitrogen-containing organic substrates.