A basic understanding of the structure property relations and how they are influenced by the molecular architecture is imperative for the future development of polymer thin films in a large number of applications including those in the electronics industry. A new study has been illustrated in this work to demonstrate the effect of an aromatic Chlorine Hydrogen substitution on the structural and dielectric properties of poly-para-xylylene (parylene N) ((-CH2-C6H6-CH2-)(n)). X-Ray Diffraction (XRD) analysis reveals that the chlorination of the aromatic rings of poly-para-xylylene stabilize the crystalline structure of the materials (alpha-monoclinic), increases the d-spacing, decreases the crystallinity, and increases the value of the dielectric parameters. Furthermore, the permittivity is increased from 2.68 (PPX N) to 3.1 (PPX C) and the conductivity is increased by two order of magnitude at room temperature at frequency 1 KHz. Fourier Transformation Infrared Spectrometer (FTIR) and Energy Dispersion X-ray (EDX) analyses shows that the different as deposited parylene type are deprived of extrinsic polar bonds who can influenced on the dielectric properties. The increase of the dielectric properties and the changes of the morphologies structure are associated to the change in the intermolecular interaction due to the Cl-H aromatic substitution of poly-p-xylylene. (C) 2012 Elsevier Ltd. All rights reserved.