The present work aims to investigate and develop a series of coumarin dyes containing benzimidazole group for the polyester fabrics , lese dyes were obtained by the condensing 2-benzimidazolyl acetic acid with salicylaldehyde, 4-N,N-diethylaminosalicylaldehyde or condensing ethyl 2-benzimidazolyl acetic acid with 2,4-dihydroxybenzaldehyde in the present of piperidine. These dyes were dyed on polyester and nylon, and their dyeing and fastness properties evaluated. The fastness properties of all the dyed samples were in accord with commercial requirements except dry heating of dye F which was dyed in 1.5% O.w. f.
