The goal of this study is to calculate the electron density, effective atomic number, mass attenuation and mass energy absorption co-efficient and kinetic energy released per unit mass for five different monomers, which are used in the polymer gel dosimeter in radiotherapy application. Power law method and Auto-Zeff software were used to calculate the effective atomic number. National Institute of Standard and Technology (NIST) database was used to calculate mass attenuation and energy absorption coefficient. Electron density of the acrylamide was higher (3.40E + 23 e/cm3) than other monomers and N-isopropyal acrylamide has least electron density (2.76E + 23 e/cm3). Each monomer has an identical effective atomic number over the energy range from 0.01 to 20 MeV. The rapid fall occurred in the kinetic energy released per unit mass at low energy. At low energy region kinetic energy released per unit mass of acrylic acid was higher than others and it was opposite in higher energy region. The behaviour of kinetic energy released per unit mass and effective atomic number similar with function of energy. Effective atomic number of n-vinyalpyrrolidine has good agreement with water (0.003 % discrepancy).