Considering that agglomerates are subject to breakdown into individual flocs under shear, a theoretical model is developed to describe the shear viscosity behavior of flocculated suspensions using the Robinson equation eta(a)/mu0 = 1 + kphi/(1 - phi/phi(max)) The rheological properties of coal-oil mixtures (COM) have been investigated using a concentric cylinder rotational viscometer in the coal volume fraction range of 0.268-0.375 at 55-85-degrees-C. The model successfully accounts for the effects of solid concentration and shear rate on rheological behavior of flocculated suspensions of irregularly shaped particles. The experimental results show that the agglomerates are densely packed with flocs, and are broken into small fragments under shear. The effect of temperature on the rheological behavior is also examined. By applying the shear rate-temperature superposition method, it was found that the bulkiness of agglomerates increases above 75-degrees-C, leading to a change in the rheological properties of COMs.