Aim: The aim of this study is to identify and characterize newly formed copolymers by modifying methyl methacrylate (MMA) monomer by substituting cycloaliphatic monomer using Fourier transform infra-red (FTIR) spectroscopy. Materials and methods: Heat-cure polymethyl methacrylate (HC-PMMA) experimental specimens were made by dissolving tricyclodecane dimethanol diacrylate (TCDDMDA) at 10% and 20% concentrations in commercially available MMA monomer. Specimens made without TCDDMDA served as the control. The specimen was then scrapped and mixed with dried potassium bromide (KBr) to form pellet. Each pellet was placed in a FTIR spectrometer and 10 scans were recorded with a spectral resolution of 4 cm⁻¹. A mean of scans was automatically processed and deduced by the system software and a final transmittance spectral graph was obtained for one specimen. Results: Three significant spectral differences exist between control and experimental groups. The first difference was the disappearance of weak peak at 1637.34 cm⁻¹ (alkenyl C=C stretch) in both experimental groups. The second difference was the appearance of new moderate broad peaks at 1482.25 cm⁻¹ and 1449.56 cm⁻¹ in both experimental groups which are attributed to the ring –CH₂ asymmetric bending (C–H deformation) vibrations. The third difference was the appearance of another new weak peak at 1386.57 cm⁻¹ in both experimental groups. This new peak confirms the formation of a new structure of copolymer. Conclusion: TCDDMDA copolymerizes with MMA, thereby decreasing the uncured residual monomer in the polymerized specimens. Clinical significance: Copolymerization of TCDDMDA with MMA would lead to the development of new monomeric composition for the fabrication of dentures possessing better mechanical properties and biocompatibility.