The rheological behavior of polystyrene melts filled with different loadings of Sn-Pb alloy has been studied. The filled polystyrene melts showed a pseudoplastic behavior, and the viscosity varied dramatically at the melting point of the alloy. The temperature dependence of the viscosity has been found to follow two separate Arrhenius equations for high and low temperatures, respectively. The presence of alloy filler was found to increase melt viscosity below the melting point of the alloy, but decreased it on reaching the alloy melting point. The melt elasticity was found to decrease with increase of alloy concentration, and increase abruptly at the alloy melting point. However, viscous flow was the dominant mechanism of deformation over the entire range of temperature studied.