Low cost fly ash-supported Cu, Co and Ni metal catalyst systems were prepared by the reduction of Cu2+, Co2+ and Ni2+ ion adsorbed raw fly ash particles by using sodium borohydride (NaBH4) as reducing agent in aqueous media and were used in catalytic studies. For this purpose firstly raw fly ash particles were characterized by scanning electron microscopy (SEM), particle size analysis, X-ray diffractometry (XRD), X-ray fluorescence spectrometry (XRF) and inductive coupled plasma-optic emission spectroscopy. Afterwards, the prepared fly ash-metal composite materials were used as catalyst for the reduction of 4-nitrophenol (4-NP) in the presence of NaBH4 aqueous solution. The reduction studies were completed at four different temperatures (20-50 degrees C). The activation parameters were calculated from the obtained rate constants for the four different temperatures (20-50 degrees C). The activation energies for the reduction reaction of 4-NP utilizing fly ash-Cu, Co and Ni composites as catalysts were 26.81 kJ mol(-1), 32.89 kJ mol(-1) and 34.98 kJ mol(-1) respectively. The total turnover frequency (TOF) for fly ash-Cu, Co and Ni composite catalysts were 0.278 mol 4-NP (nnol Cu)(-1) (min)(-1), 0.033 mol 4-NP (mol Co)(-1) (min)(-1) and 0.024 mol 4-NP (mol Ni)(-1) (min)(-1), respectively.