The slips intended for the manufacture of ceramics must have rheological properties well-defined in order to bring together the qualities required for the casting step (good fluidity for feeding the molds easily settles while generating a regular settling of the dough and for the dehydration phase of the dough in the mold a setting time relatively short is required to have a sufficient refinement which allows demolding both easy and fast). Many additives have added in slip of ceramic in order to improve their rheological and mechanical properties. In this study, we investigated the impact of xanthan gum on rheological and mechanical properties of ceramic slip. The modified Cross model is used to fit the stationary flow curves of ceramic slip at different concentration of xanthan added. The addition of xanthan gum in a concentration range between 0 and 0.4 wt % in slip of ceramic induces the increase in the yield stress, zero shear rate viscosity and the infinite shear rate viscosity of the slip of ceramic. Generally speaking, the presence of xanthan gum modifies the rheological and mechanical properties of the slip. On the other hand, the study shows that an increase in flexural strength with the increase of the amount of xanthan gum in the ceramic slip. All the experimental results indicate an increasing tendency of the interactions between the particles of the raw materials with the highest concentration of xanthan gum.