Impinging jet atomization is an effective method to produce fine sprays for extremely high viscosity fuels such as coal water slurry (CWS). This technique has been used successfully in a number of CWS applications since its inception. The purpose of this study is to analyze the effect of liquid viscosity and jet velocity in an impinging jet atomizer with a combined volume of fluid (VOF) model. It is observed that the film thickness increases with increased liquid viscosity, and the (a) relative velocity between the liquid and gas phase, (b) the gas liquid ratio (GLR), and (c) the atomizing gas pressure all play important roles. Mean droplet size predicted with the VOF model agrees well with experiments.