In this work the thixotropy of organically modified clay suspensions was experimentally studied. Mixtures of a modified hectorite and gasoil were prepared at different concentrations. Four experimental sets were used to characterize the thixotropic behavior of the suspensions. It has been shown that modified hectorite suspensions exhibit a time-dependent non-Newtonien behavior. Hysteresis loop measurements showed that the suspensions exhibit a thixotropic behavior at high shear rates and an anti-thixotropic behavior at low shear rates. It was found that shear rates at the intersection of the loading and the unloading curves are dependent to the concentration of the modified clay suspension. Build up experiences from an initial high shear stress value to a shear stress in the intersection domain have shown that an equilibrium between breaking-down and building-up of the microstructure is established in the zone separating the thixotropic and the anti-thixotropic behaviors. Both of the Carreau-Yasuda and the Herschel-Bulckley models were used to fit the loading flow curves. Equilibrium shear rates at constant shear stresses starting from a rest structure were plotted and compared to the flow curves. A good matching of the Herschel-Bulckly model parameters, applied on both the equilibrium and the flow curves, was found. Plots of the shear rate as a function of time, after a sudden change (diminishing / increasing) of the shear stress from an initial value (Build-up / Break-down), have illustrated the time dependency of the modified hectorite after reaching a reference intern structure state. These results will be used to describe the kinetics evolution of the suspensions.