The effect of heavy liquid fuel properties on the atomization characteristics is introduced. Detailed measurements of the drop size and the velocity distribution were obtainl!d for a twin fluid externally mixing atomizer. The Phase Doppler Particle Analyzer is used in the current measurements. The simultaneous measurement of drop size and velocity was the major importance in accurately describing the changes in the local drop size distributions and mass flux. Result M.141 SHABANA H. WasON S.A. SYAM A.R.shows a noticeable decrease in droplet size distribution and the corresponding droplets velocity with increasing fuel temperature. A mathematical model was developed to predict the atomization process. The stochastic separated flow model (SSF) at well as modified interaction mechanismktween the two ,nases of thespray were taken into account to improve the capabilities of the prediction method.