Water plays major role in the day-to-day activities of the societies and other living things. However, fresh water is becoming polluted due to increased discharge from manufacturing industries in the form of effluents into the environment. Therefore, the effluent needs to be treated before discharged to the environment. In this work, Zinc oxide (ZnO) and Al doped ZnO photocatalysts were synthesized by sol–gel method using zinc acetate as precursor for degradation of methylene blue dye (one of toxic effluents from textile industries). The characterization of the synthesized samples were performed by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and UV visible (UV VIS) spectroscopy. The XRD result revealed the presence of a hexagonal wurtzite structure. The FT-IR results showed predominant absorbance peaks at maximum peak 864cm-1, 712cm-1 and 506 cm-1, which corresponds for Al-O, Al-O-Zn and Zn-O bond stretching, respectively. Similarly, the result obtained from UV-VIS revealed the bandgap energy of ZnO changed from 3.05 eV to 3.1 eV, due to doping effect by Al. SEM images show the morphology of ZnO and Al-ZnO NPs. EDS mapping confirms the presence of O and Zn. Finally, the photocatalytic performance of the samples were investigated over a wide range of operating parameters and it has been obtained over 99.3 % degradation of methylene blue in 120 minutes of irradiation time, under light intensity of 5810 lux, using 2% Al doped ZnO nanoparticles at 65 °C reaction temperature. Degradation efficiency increased with increasing light intensity, dopant amount, reaction temperature, and contact time.