In this study, Zinc oxide (ZnO) nanowires (NWs) were successfully produced on Zn plates through electrochemical anodization in potassium bicarbonate aqueous electrolytes with different production parameters in two groups as applied voltage and anodization time. Subsequently, the ZnO NWs were annealed at 300 ℃ for 1 h in air atmosphere to increase crystallinity and remove organic residues. Structural and morphological properties were determined through X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. The effect of anodization parameters on the structure of ZnO NWs and thus their photocatalytic activities were evaluated in detail by UV spectrophotometer. The results pointed out that, the most effective nanostructure on the photocatalytic degradation of methylene blue was obtained at the sample anodized under 30 V for 30 min at room temperature with 90.6% degradation efficiency among the samples. This result shows that the NW structured ZnO materials are promising to be used as effective photocatalysts in the removal of organic pollutants by solar energy and their conversion to green compounds.