A novel heterogeneous Fentons catalyst for the destruction of pollutants in waste waters by the decomposition of H2O2 was produced by modifying a polyacrylonitrile (PAN) fibre by treatment with a mixture of hydrazine (HD) and hydroxylamine (HA) to introduce chelating functional groups onto the fibre surface. These functional groups are used to ligate the transition metal cations Fe3+, Co2+, Ni2+ and Cu2+ to the fibre to act as the active catalytic sites for decomposition of the hydrogen peroxide. The hydrazine and hydroxylamine concentrations in the modifying solution, pH and duration of alkaline treatment were optimised with respect to the strength of the metal fixation on the polymer matrix and the rate of decomposition of hydrogen peroxide in aqueous solution. The optimum conditions were found to be [N2H4] = 30 g/l, [NH2OH] = 42 g/l, pH 9.5 followed by a further alkaline treatment of short duration. The fibrous catalyst produced was successfully tested in real textile effluent oxidation from dyeing and finishing processes and showed potential in the area of effluent treatment particularly in advanced oxidation processes for the oxidative decomposition of organic pollutants in industrial effluents and waste waters.