The theological behaviour of xanthan gum was determined at various temperatures (20-100 degrees C) and concentrations (0.3-1.3%), and was found to be most adequately described by a power-law model. The effect of temperature on the viscosity followed an Arrhenius relationship, whereas the effect of concentration followed an exponential relationship. A number of models to predict the visosity as a function of shear rate, concentration and temperature are presented The models developed had an excellent fit and would be useful for manufacture and applications of xanthan gum.