Abstract: Background and Objective: Water pollution is a worldwide issue that attracted the researcher’s attention. It involves the release of toxic substances, pathogenic germs, easy-soluble substances, radioactivity, etc. These pollutants affect human health, aquatic living and microorganisms. This study aimed to use modified ZnO nanoparticles as an affordable technique for the purification of water from dyes and heavy metals. Materials and Methods: In attempt to improve methylene blue photodegradation rates using ZnO, a series of tin oxide (SnO2) doped ZnO photocatalysts were synthesized using sol-gel method with a doping molar ratios (0, 0.01, 0.02, 0.04 and 0.05 M) SnO2/ZnO. The prepared photocatalysts were characterized by XRD (X-Ray Diffraction), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM) and Diffuse Reflectance Spectra (DRS) in order to investigate their morphology, structures and band gab. Results: The crystallinity and the average grain sizes of ZnO decreased with increasing the amount of SnO2. The DRS showed a reduction in band gap energy from 3.27-3.10 eV by increasing SnO2 molar ratio. The percentage of degradation dropped, when the initial dye concentration increased. The amount of adsorbed metals on SnO2 doped ZnO surface increased by increasing SnO2 molar ratio then decreased at 0.05 M SnO2 doped ZnO. Conclusion: The SnO2 doped ZnO photocatalyst demonstrated the highest photodegradation efficiency which was about 100% in 90 min and higher adsorption efficiency to all studied heavy metals which was nearly 100% to all metals in 1 h.