Water soluble monoazo dyes which, in the form of the free acids, have the formula:
wherein A represents the residue of a diazo component of the benzene series containing a single sulphonic acid group and optionally one or more other substituents, R' represents hydrogen or lower alkyl and each of R2 and R3 independently represents hydrogen, optionally substituted alkyl or phenyl, or R2 and R3 together with the nitrogen atom to which they are attached form a saturated ring.
The dyes are applicable as acid dyes to natural and synthetic polyamide textile materials on which they give fast bright yellow shades.