This research synthesised zinc oxide (ZnO) structure by a hydrothermal method. ZnO samples were prepared using different molarities of zinc (Zn) precursor, ranging from 0.10 to 0.16 M. Structural and morphological properties were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD patterns show that all samples are prominently grown along the three diffraction peaks at (001), (002) and (101) planes. The ZnO sample with 0.16 M Zn precursor has the highest peak orientation along the (002) plane. The average crystallite sizes for the ZnO structure with 0.10, 0.12, 0.14 and 0.16 M precursor are 48, 51, 49 and 31 nm, respectively. ZnO sample prepared at 0.16 M has the smallest crystallite size and the lowest tensile strain. The SEM images show that the ZnO samples are randomly oriented with average diameters of 209, 325, 295 and 348 nm when using 0.10, 0.12, 0.14 and 0.16 M of the precursor, respectively. The electrochemical behaviour of the ZnO structure was determined through cyclic voltammetry (CV) measurement. In the CV curve, the calculated specific capacitance for the ZnO sample prepared at 0.16 M has the highest value of 3.87 Fg−1. The ZnO sample prepared at 0.10 M has the lowest specific capacitance value of 2.11 Fg−1. Therefore, changing the molarity of the Zn precursor could change the structural and electrochemical properties. ZnO sample prepared with 0.16 M of the precursor provides the optimal result.