This paper aims to gain a better understanding of the flash atomization of a hydrocarbon solution containing n-hexadecane and n-butane, with nitrogen as the propellant gas. The nitrogen flow rate, injection temperature, and butane concentration were varied. Breakup pattern and spray quality were characterized by taking images at the nozzle exit. Mean droplet diameters were measured as a function of operating conditions. It is shown that the atomization of n-hexadecane can be significantly enhanced by using butane as a propellant liquid. For a given mean drop size, the presence of butane can markedly reduce the propellant-gas-to-liquid ratio. A simple and practical correlation for the Sauter mean diameter was developed, taking the form SMD (mum) = 118.4 - 28.3(DeltaT* - K) where DeltaT* and K are a dimensionless degree of superheating and the cavitation number, respectively. This correlation collapses all the data under diverse conditions into a single curve. (C) 2004 Elsevier Ltd. All rights reserved.