Abstract. Polycrystalline Pb(Mn0.5W0.5)O3, (PMW), a ferroelectric oxide, having perovskite structure was prepared by high temperature solid state reaction method. Structural and microstructural properties of PMW compound were studied by the X-ray diffraction (XRD) technique and scanning electron microscopy (SEM). In order to reduce the measurement error caused by edge capacitance, laboratory-made three-terminal guard ring electrode was constructed. Guard ring electrode was generally applied to electrode system of the material for the measurements of insulation resistance and dielectric constant. The frequency dependences of the capacitance (C), dielectric constant (εr), loss tangent (tan δ), volume resistivity (ρv) and surface resistivity (ρs) of PMW ceramics were investigated at different annealing temperatures. The PMW ceramics (300 °C) exhibited the smallest value of capacitance gap (the smallest error = 3.26 %) at 1 kHz while the maximum degree of capacitance gap was caused at PMW ceramics at 500 °C at 100 kHz. The smallest value of volume resistivity and surface resistivity were found to be 1.6×10-4 MΩ-cm and 0.0599 MΩ-cm respectively.