Tripler synfuels composed of residual oil, pulverized coal and water (OCWF) have been prepared. The ratio of the components oil (O) to coal (C) to water (W) by weight was O:C:W = 4:2:4 for water-based synfuel, and O:C:W = 5:2:3 for oil-based synfuel. It has been found that the rheological behaviour of water-based synfuel followed the Herschel-Bulkley model, whereas that of oil-based synfuel followed the Bingham model. An investigation of temperature dependence of their viscosities showed that the viscosity-temperature characteristic of both synfuels followed Arrhenius equation at fixed shear rates. The flow activation energy values of oil-based and water-based OCWF equaled 71.53 kT mol(-1) and 16.16 kT mol(-1) (at shear rate 29.13 s(-1)) which kept the sequence of the flow activation energy values of residual oil and distilled water, implying that the viscosity of OCWF was mainly determined by that of the dispersion medium. Compared with the flow activation energy values of dispersion mediums, those of two OCWFs were larger. It is reasonable to assume that the excess part of the flow activation energy was caused by the interaction between particles in OCWFs, and the equation eta = Aexp[(E + S)/RT] has been proposed.