Experiments were conducted in order to investigate the influences of flow rate, applied voltage, and electric conductivity on droplet size and size distribution of water electrosprays in the simple-jet mode. The results show that the electric potential decreases significantly the relative standard deviation (RSD) of the spray size distribution, with the best result obtained for Weber number, We?=?3.3 (240?ml/h) when the RSD decreases from 0.50 at 0?kV to 0.18 at 5?kV. We conclude that simple-jet mode electrosprays are a good option for applications which require monodisperse micrometer droplets with high throughput.