Concentrated suspensions of charged stabilized colloidal particles exhibit very large viscosity at low shear rate, a strong shear-thinning behavior at intermediate shear rate, and a constant second Newtonian viscosity at high shear rate. This type of non-Newtonian behavior is affected by many factors such as the particle volume fraction phi, the particle diameter, the surface electric potential psi(0), salt concentration, etc. The generalized equation for the viscosity eta of this system is proposed by applying Eyring’s transition state theory. The surface electric potential psi(0) and the thickness of the electric double layer k(-1) are determined by applying the theory to experimental data. Systematic experiments of eta of the model colloidal dispersion systems are carried out as the function of phi and shear rate and the results are satisfactorily reproduced by the present theory. The effects of hydrodynamic diameter d(h) and psi(0) of the colloidal particle on eta are also quantitatively explained.