The mass attenuation coefficients (μm) of polyethylene glycol (PEG) of different molecular weights (1000–200,000) were measured using single-beam photon transmission. The X-ray fluorescent (XRF) photons from Zinc (Zn), Zirconium (Zr), Molybdenum (Mo), Silver (Ag) and Cadmium (Cd) targets were used to determine the attenuation of gamma radiation of energy range between 8.67 and 23.19 keV in PEG samples. The results were compared to theoretical values using XCOM and Monte Carlo simulation using Geant4 toolkit which were was developed to validate the experiment at those certain energies. The mass attenuation coefficients were then used to compute the effective atomic numbers, electron density and half value layers for the studied samples. The outcomes show showed good agreement between experimental and simulated results with those calculated theoretically by XCOM within 5% deviation. The PEG 1000 sample showed shows slightly higher more μm value compared with the other samples. The dependence of the photon energy and PEG composition on the values of μm and HVL were are investigated and discussed. In addition, the values of Zeff and Neff for all PEG samples behave behaved similarly in the given photon energy range, and they decreased decrease as the photon energy increased increase.