A solid by-product formed as deposits in the pyrolysis process of poly(acrylonitrile-co-methyl methacrylate) was analyzed. Two main
components, namely ammonium sulphate and 1,3,5-tricyanobenzene were identified by IR, GC-IR, TG-MS and XRD techniques. The
major organic components, 1,3,5-tricyanobenzene was crystallized from acetone extract as colourless needles. 1,3,5-Tricyanobenzene
proved to be a mutagenic active agent by bacterial (Salmonella typhimurium TA98 and TA1537) reverse mutation assay.
Key words: 1,3,5-tricyanobenzene; acrylonitril-co-methyl methyacrylate fiber; carbonization; mutagenic effect