Abstract For the present study, the cotton fabric and dye solution were irradiated to UV radiation for different times. Dyeing was performed using un-irradiated and irradiated cotton with un-irradiated and irradiated reactive blue dye. Different dyeing parameters such as temperature, pH and time were optimized using irradiated dye and irradiated cotton. The data of colour report were obtained from un-irradiated and irradiated cotton dyed with reactive blue dye using spectra flash (SF650). Colourfastness properties show that UV radiation of both cotton and dye powder has improved the grading of fastness from fair to good. It is found that UV irradiation has not only enhanced the strength of dye on irradiated fabric but also improved the dyeing properties.