Cooling time in soft tooling process using conventional mold materials is normally high. Although increase of effective thermal conductivity of mold material by inclusion of high thermally conductive fillers reduces the cooling time, it affects other properties (namely, stiffness of mold box and flow ability of melt mold material), which play important roles in soft tooling process. Therefore, to apply composite polymer in soft tooling process as mold material simultaneous studies of these properties are important. In this work, extensive experimental studies are made on the effective thermal conductivity, modulus of elasticity and viscosity of composite polymeric mold materials namely Polyurethane and RTV (Room Temperature Vulcanizing)-2 silicone rubber, with aluminum and graphite particle reinforcements. To find suitable models of the effective properties of composite mold materials, which are required to decide the optimum amount of filler content before actual application, attempts are made to fit the experimental results using various models reported in the literature. Finally, different aspects in reducing cooling time in soft tooling process and further activities are reported. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012