Polymers have become an alternative option replaces the high voltage insulation materials made of ceramic and glass. The research aims to determine the dielectric characteristics of polymer insulation after water immersion for a certain period of time. The testing was conducted on two types of polymer insulation, namely the epoxy resin and the cross-linked polyethylene cable. The materials were soaked in water with the temperature of 50oC and the measurements were taken every 24 hours for 38 days. The measurements were taken from the mass materials, the relative permittivity and the contact angle. Then, the breakdown voltage measurement and the analysis of the chemical structure of the polymer insulation material were measured when the material had reached saturation state. The research results indicate an increase in the value of the mass and the relative permittivity of the material after the immersion. Such increase level is due to the absorption of the water through the filler in the polymer insulating material. The contact angle value of the epoxy resin material ranged from 56o-80o, which was classified in the category of partially wet. The XLPE material has the value of the average contact angle of above 90o and in the category of hydrophobic. The breakdown voltage value has decreased by 50% in average from the voltage limit before the immersion. The water absorption process has an effect on the decrease of the dielectric strength of the insulating polymer material
