Ternary composites of natural rubber filled with particulate carbonaceous and metal fillers were developed for electro-mechanical sensing purposes, while maintaining good elasticity and loading capability. The effects of filler type and composition on electrical and mechanical properties of binary and ternary conductive composites have been examined. The typical mechanical-compounding and molding processes for rubbers were used for this study. As observed, the binary composite containing 50 phr carbon black in natural rubber was the superior conductive composite for a pressure sensor based on its balance of compression set and electrical conductivity. At the same total filler content, a third metal component filler decreases the electrical conductivity of the binary composites. In addition, the third component of metal fillers deteriorates the compression set of the composites.