Investigations were carried out on polycaproamide films(PCA) at room temperature in air. Samples were dyed with oxyethylsulfonic and monochlortriasinic active dyes. Irradiation was carried out with a low-pressure Hg lamp (λ = 254 nm, intensity equals 1.5 × 1015 sm−2 sec−1). During irradiation, ESR spectra of five poorly resolved lines of superfine structure were observed for all samples. Analysis of ESR spectra shows that quintet belongs to radicals . The initial accumulation rate of radicals was measured on linear parts of radical accumulation curves. Similarly, accumulation of PCA carboxyl groups kinetics was measured. The initial accumulation rates of radicals and carboxyl groups are linear functions of absorbed radiation on polymer and dye. There is a tendency of increasing carboxyl group yields with radical yields for different dyes. One can assume that it follows from this correlation that radicals are precursors of carboxyl groups. Luminescence spectra measured for PCA with salt and covalent bonded dyes are located near 425 nm. The data allow the conjecture that PCA luminescence is connected with centers bonded with PCA macromolecules.