This dataset supplements the manuscript with the title “Unveiling the potential of using a spar-buoy oscillating-water-column wave energy converter for low-power stand-alone applications”, Applied Energy, doi:10.1016/j.apenergy.2021.116835 The dataset includes the irregular-wave time-series that allows the reproduction of the results presented in Figs. 15, 16, 17, and 18, using a larger orifice plate (OS3). The data may be used for result reproduction, numerical modelling validation, and control purposes. We present all data at model-scale, which was 1:10th, using Froude scaling criterion. You may find data for two significant wave heights Hs [m], and for several energy periods Te [s]. Each excel file includes the time-series of the following: • the pressure difference (tab 1, column B), • the relative motion between the buoy and the oscillating-water-column (OWC) (tab 1, column C), • the free-surface-elevation as it was recorded by the wave gauge next to the buoy (tab 1, column D), • the motions in six degrees-of-freedom (tab 2). The calibrations have already been applied to the data, and all time-series have been filtered. Below you can find the number and main characteristics (sea-states) for each excel file (the significant wave height Hs [m] (rounded value) and the energy period Te [s], at model scale): Test (65): Hs = 0.1 m, Te = 1.76 s Test (66): Hs = 0.1 m, Te = 1.80 s Test (67): Hs = 0.1 m, Te = 2.02 s Test (68): Hs = 0.1 m, Te = 2.50 s Test (69): Hs = 0.1 m, Te = 3.23 s Test (70): Hs = 0.1 m, Te = 3.58 s Test (71): Hs = 0.1 m, Te = 4.88 s Test (73): Hs = 0.2 m, Te = 2.30 s Test (74): Hs = 0.2 m, Te = 2.67 s Test (75): Hs = 0.2 m, Te = 3.19 s Test (76): Hs = 0.2 m, Te = 5.02 s