Introduction: In medical physics applications, effective atomic numbers are often employed to set apart and specify the interaction of ionizing radiation with matter. Methods: The effective atomic number of soy-lignin bonded with Rhizophora spp. particleboards were analyzed using Energy Dispersive X-ray analysis and Carbon Hydrogen Nitrogen Analyzer. The effective atomic number were compared and recorded with reference to the effective atomic value of water. Results: The result showed that the effective atomic number calculated for adhesive bound Rhizophora spp. samples were close to effective atomic value of water, with 3.34 – 3.47 % differences by using Energy Dispersive X-ray and 6.47 – 6.78 % differences by using Carbon Hydrogen Nitrogen analysis. The result revealed that through Energy Dispersive X-ray method, the effective atomic number was much closer to water compared to Carbon Hydrogen Nitrogen analysis. Conclusion: Despite the availability of hydrogen content in the samples in Carbon Hydrogen Nitrogen analysis, Energy Dispersive X-ray method was much more preferred and gave better result compared to Carbon Hydrogen Nitrogen analysis thus provide a compelling argument for the use of Energy Dispersive X-ray method to measure the effective atomic number of Rhizophora spp. particleboard in medical physics applications.