The complex potassium trioxalatoferrate (III) trihydrate {K-3(Fe(C2O4)(3) center dot 3H(2)O)} was synthesised and characterised by energy dispersion X-ray fluorescence (XRF) and X-ray diffraction (XRD). The electrical and dielectric properties of the complex pellet were studied by ac- and dc-techniques in room temperature and in a temperature range of 293-373 K. The data of the ac conductivity as a function of frequency in a frequency range of 1-100 kHz follow the correlated barrier hopping CBH model and the parameters of the model were determined and connecting them with the optical properties. The temperature dependence of dc conductivity shows that the semiconducting behaviour of conduction phenomenon in the complex is realised by hopping mechanism between localised states and the minimum hopping distance was determined. High relative permittivity of about 30 at 100 kHz was obtained for the complex, which can find technological applications like alternative for the SiO2 insulator in MOS devices. (C) 2007 Published by Elsevier B.V.