The electric properties of hybrid organic-inorganic nanostructured coated XLPE are investigated in this paper with the purpose to understand if this class of nanostructured insulating material could have applications in the field of high voltage electrical insulation. Space charge measurements and aging tests under partial discharge activity were performed on different kinds of nanocoated specimens and the results compared to the base XLPE. The paper shows that space charge accumulation can be reduced significantly by some coatings which could increase the injection barrier. Moreover, surface erosion caused by partial discharges can be slowed down even by a thin coating of about 1μm, which creates a ‘barrier effect’ to partial discharge propagation in the insulation bulk.