Zinc peroxide (ZnO2) and zinc oxide (ZnO) nanoparticles have interesting properties. Thus, they have the potential to be applied as optoelectronic devices. Pulsed laser ablation in liquid (PLAL) method is one of the top-down synthesis methods which have several advantages, such as its low cost, no need for a vacuum environment, and relatively fast synthesizing nanoparticle materials. Nd-YAG laser with a second harmonic generator was used as the laser beam source for the experiment. The mixture of zinc powder, deionized water, and hydrogen peroxide (H2O2) as oxidizing agent was treated by the PLAL method. Heating treatment was applied to the samples. X-ray diffraction, UV-vis spectrophotometry, and Fourier Transform Infrared (FTIR) were applied as the sample characterization methods. X-Ray diffraction characterizations confirmed ZnO2 nanocrystal and ZnO nanocrystal, which were synthesized from ZnO2 through an annealing process. From UV-vis spectrophotometry, the values of 4.57 eV and 3.33 eV were obtained as the bandgap energy for ZnO2 and ZnO, respectively. FTIR spectra shows absorption peaks for ZnO2 and ZnO.