An experimental study to assess the accuracy of a wire-mesh sensor with a temporal and spatial resolution of 5 kHz and 4.8 mm in dependence of bubble size has been carried out. As a reference, single air bubbles with a defined bubble size of 2 - 12 mm are injected in a stagnant liquid phase. The results show a higher uncertainty for bubble diameters below the grid resolution of the sensor. In this case, the bubble size depends strongly on the local bubble position within the mesh grid during its passage.