Droplet size distributions from the bulk flashing of 50°C superheated water were measured experimentally. The distributions were lognormal, with a geometric mean droplet diameter Dg of 124 µm and a geometric standard deviation σg of 1.30. Measured droplet size distributions at 40 and 30°C superheat were also lognormal, but the values for Dg and σg were not sufficiently reproducible to compare to the 50°C superheat results. Flashing occurred from a 16.4-ml chamber through a 19-mm-diam opening. The door opening time was 1.6 ms. Measurements were made by collecting droplets containing blue dye on paper mounted on a rotating bicycle wheel. Spot sizes were correlated with droplet sizes using neutron activation analysis by adding samarium nitrate to the water and activating the samarium. Measurements of pressure, temperature, and expansion velocity during the flashing process were made and compared with calculated values with moderately good agreement. Exploratory calculations of maximum droplet diameters based on the critical Weber number (aerodynamic fragmentation) were made with results within a factor of 2 or 3 of the measured values.