Abstract: A process for dyeing keratinous fibers such as hair which comprises reacting the hair with a dyestuff of the general formula ##EQU1## where X is a chromophoric group, such as a group formed by coupling a phenylene diazonium salt with a diazo coupling compound, and where R has the formula --R'COOH, --R'COOCH.sub.3, --CH.sub.2 CH.sub.2 OH or --CH.sub.3 in which R' is an alkylene group containing 1,2 or 3 carbon atoms. The process gives good coloring of hair without damaging the condition.The invention also relates to novel dyes for use in the process and to processes for their production, and to dyeing compositions containing the dyes.