A process for the continuous dyeing of textile materials containing or consisting of synthetic fibrous materials from organic solvents, which comprises impregnating the said textile materials with an organic dyebath containing at least one dyestuff of the formula ##SPC1##In which the phenyl radical A is unsubstituted or substituted by 1 to 3 substituents of the group consisting of halogen, nitro, cyano, trifluoromethyl, lower alkyl, lower alkoxy and lower alkoxy-lower alkylene--O--, B represents naphthylene or ##SPC2##R.sub.2, r.sub.3, r.sub.4 and R.sub.5 each represent hydrogen, halogen, lower alkyl, lower alkoxy or lower alkoxy-lower alkylene--O--, and R.sub.1 stands for a linear or branched alkylcarbonyl of at most 18 carbon atoms, ##SPC3## ##SPC4## ##SPC5## ##SPC6##And an organic solvent, and fixing the dyestuffs by submitting the impregnated materials to a heat treatment.