In order to determine the effect of catalyst loading, a series of experiments were carried out on NB solution with 2.52* 10-4 M content and pH = 7, by varying the (0.5 wt.%Fe)–TiO2 photocatalyst dose between 50–500 mg/L. From determined pollutant concentration at various irradiation times (60–240 min.) the NB degradation efficiency and rate constant to each applied catalyst dose were calculated.