The rheological behavior of individual solutions and blends of xanthan gum (0.1 to 0.5 %) and pectin (1.6 to 2.0 %) was studied at 25, 50 and 75 °C using a D-optimal mixture experimental design. Pectin and xanthan gum solutions were found to be Newtonian and non-Newtonian fluids, respectively. The effect of the temperature on the viscosity of pectin solutions and the consistency index (K) of xanthan gum were modeled by the Arrhenius equation. The xanthan gum/pectin mixtures predominantly behaved as pseudoplastic fluids and were described by the power law model. Mathematical models were developed to predict the flow behavior index and the consistency index as a function of the blends composition, at the studied temperature. The activation energy of flow was expressed in terms of the concentrations of the components of the mixtures. The obtained mathematical models are useful for predicting the rheological parameters of pectin and xanthan gums blends and for evaluating possible applications.