In the case of the electrically conductive master batch (ECMB) for fibers application, higher filler content required to produce adequate conductivity can be accompanied by a reduction in spinnability and mechanical property of final fibers. To minimize these problems, ECMB with the character of lower percolation threshold was designed in this article. Carbon black (CB) was treated by titanate coupling agent. Polymer blend poly(ethylene terephthalate) (PET) /polyethylene(PE) was used as matrix instead of individual polymer matrix. The effects of titanate coupling agent treatment and the composition of polymer blend on the properties of ECMB have been discussed. FTIR and laser particle size distribution analyzer were employed to study the CB. Solubility tests and positive temperature effect peak were used to verify the distribution of CB in the polymer blend. These results showed that CB treated with 2 wt % titanate coupling agent and PET/PE polymer blend with the weight ratio of 60/40 appear to be an effective way to design the ECMB with a low percolation threshold. (c) 2006 Wiley Periodicals, Inc.