The synthesis and dyeing properties of several basic dyes, obtained by quaternization of pyridine or triethylamine with p substituted p‐chloroacetylaminoazobenzene are described. The compounds, applied as cationic dyes on acrylic fibre, show good fastness to light and wet treatments. The uptake of pyridine‐containing dyes is higher than that of the corresponding triethylamine derivatives. On increasing pH, an increase in dye uptake isobserved, whereas, on increasing dyebath concentration, the dye adsorption increases greatly. The dyeing rate and times of half‐dyeing are disc