Low-density polyethylene (LDPE)/ZnO composites were prepared using melt mixing process. ZnO powders with sizes of 200 nm and 2 mu m were used as reinforcing particles. The dielectric and conductivity properties of the LDPE/ZnO composites as a function of ZnO volume fraction and frequency were investigated. The results showed that the dielectric constant of the composites reinforced with micro- and nanoparticles increases almost linearly with increasing ZnO volume content. However, the resistivity of the microcomposites showed a sharp decrease when the ZnO content reaches >= 18 vol%. And the resistivity of nanocomposites started to decrease at lower ZnO content, i.e. 2.8 vol%. The critical interparticle distance between adjacent ZnO particles for low resistivity is determined to be 400 nm. From the interparticle distance concept, we determined the percolation concentration (52 vol%) for the micro- and nanocomposites. The correlation between the electrical properties and interparticle distance is investigated. (c) 2005 Elsevier B.V. All rights reserved.