The viscosity of quasi-solid emulsion phase (mu(e)) of the "homogeneously aerated, expanded emulsion phase" (HAE emulsion phase) of fine powders within the gas velocity range of minimum fluidization (U-mf) and minimum bubbling (U-mb), was obtained at ambient and elevated temperatures by measuring the strain retardation time (tau) of the HAE emulsion phase in this study. The deformation coefficient M was obtained by our previously developed experimental method [Powder Technol., 81 (1994) 177]. We confirmed experimentally that the HAE emulsion phase behaves exactly as quasi-elastic body, by observing the emulsion phase volume expansion and contraction within the velocity range of U-mf and U-mb. It is to be noted that U-mb > U-mf. The volume element of the unit HAE emulsion phase could be expanded or contracted by the force balance between the excessive gas drag force (above the gravitational force) and the inter-particle force of the particles of the emulsion phase, This experimental evidence enabled us to decide using the visco-elastic theological model of the Voigt-Kelvin model body (VK model body) in terms of mathematics to analyze our experimental data. The theological parameters, i.e., the elastic deformation coefficient (Y) and quasi-solid viscosity (mu(e)) of our experiments, were obtained by using the HAE emulsion phase. Using these experimental data together with the VK model body, we developed our experimental model equation including the measured strain retardation time (tau) to obtain the "quasi-solid viscosity" of the HAE emulsion phase (mu(e)). The physical meaning of this viscosity of the HAE emulsion phase developed in this study is quite different from the "apparent quasi-liquid viscosity" defined in aggregative fluidized beds, under the condition of U-mf = U-mb. The interesting experimental data correlations of comprehensive rheological parameters (mu(e), Y, sigma(t)) of the HAE emulsion were obtained for fine powders at ambient and elevated temperatures.