This study presents a comprehensive Fourier-Transform Infrared (FTIR) spectral library for the characterization of MXenes, a family of two-dimensional transition metal carbide and carbonitride materials. The research focuses on 12 common MXene types, including Ti₂CTₓ, Nb₂CTₓ, Mo₂CTₓ, V₂CTₓ, Ti₃C₂Tₓ, Ti₃CNTₓ, Mo₂TiC₂Tₓ, Mo₂Ti₂C₃Tₓ, Nb₄C₃Tₓ, V₄C₃Tₓ, Ta₄C₃Tₓ, and Mo₄VC₄Tₓ. The FTIR spectra were obtained by measuring delaminated MXene flakes embedded in KBr pellets over the 4000–400 cm⁻¹ range. Detailed protocols for sample preparation, data collection, and interpretation are provided. Theoretical calculations based on density functional theory (DFT) were used to assign the characteristic FTIR peaks and analyze the vibration modes. The study aims to provide the 2D materials community with a reliable FTIR spectroscopy technique for identifying and analyzing MXenes. The FTIR spectra reveal distinct vibrational modes corresponding to the chemical composition and surface terminations of MXenes. For example, in Ti₃C₂Tₓ, the C–O stretching vibration is dominant in the 1700–1550 cm⁻¹ range, while the Ti–F bending vibration is shifted due to the presence of multiple surface atoms. The study also highlights the influence of MXene composition, structure, and surface terminations on their characteristic FTIR fingerprints. Theoretical calculations support the empirical assignments of FTIR peaks, providing a deeper understanding of the vibrational modes in MXenes. The research demonstrates the importance of FTIR spectroscopy in the analysis of MXenes, particularly for identifying key O–H vibrations and surface functionalization. The study also addresses the challenges of interpreting FTIR spectra due to the complexity of MXene structures and mixed terminations. The results show that the FTIR peak positions are influenced by the thermodynamic stability of the corresponding metal oxides, with more negative Gibbs free energy values leading to higher wavenumbers in the A₂u (M–O) vibration mode. This work provides a unified approach to the FTIR spectroscopy analysis of MXenes, offering reliable recommendations for the identification and analysis of these materials. The study establishes a foundation for the FTIR analysis of MXenes and demonstrates the use of an easy and dependable FTIR technique for their characterization. The results highlight the importance of theoretical predictions in improving the accuracy of FTIR peak assignments for MXenes.This study presents a comprehensive Fourier-Transform Infrared (FTIR) spectral library for the characterization of MXenes, a family of two-dimensional transition metal carbide and carbonitride materials. The research focuses on 12 common MXene types, including Ti₂CTₓ, Nb₂CTₓ, Mo₂CTₓ, V₂CTₓ, Ti₃C₂Tₓ, Ti₃CNTₓ, Mo₂TiC₂Tₓ, Mo₂Ti₂C₃Tₓ, Nb₄C₃Tₓ, V₄C₃Tₓ, Ta₄C₃Tₓ, and Mo₄VC₄Tₓ. The FTIR spectra were obtained by measuring delaminated MXene flakes embedded in KBr pellets over the 4000–400 cm⁻¹ range. Detailed protocols for sample preparation, data collection, and interpretation are provided. Theoretical calculations based on density functional theory (DFT) were used to assign the characteristic FTIR peaks and analyze the vibration modes. The study aims to provide the 2D materials community with a reliable FTIR spectroscopy technique for identifying and analyzing MXenes. The FTIR spectra reveal distinct vibrational modes corresponding to the chemical composition and surface terminations of MXenes. For example, in Ti₃C₂Tₓ, the C–O stretching vibration is dominant in the 1700–1550 cm⁻¹ range, while the Ti–F bending vibration is shifted due to the presence of multiple surface atoms. The study also highlights the influence of MXene composition, structure, and surface terminations on their characteristic FTIR fingerprints. Theoretical calculations support the empirical assignments of FTIR peaks, providing a deeper understanding of the vibrational modes in MXenes. The research demonstrates the importance of FTIR spectroscopy in the analysis of MXenes, particularly for identifying key O–H vibrations and surface functionalization. The study also addresses the challenges of interpreting FTIR spectra due to the complexity of MXene structures and mixed terminations. The results show that the FTIR peak positions are influenced by the thermodynamic stability of the corresponding metal oxides, with more negative Gibbs free energy values leading to higher wavenumbers in the A₂u (M–O) vibration mode. This work provides a unified approach to the FTIR spectroscopy analysis of MXenes, offering reliable recommendations for the identification and analysis of these materials. The study establishes a foundation for the FTIR analysis of MXenes and demonstrates the use of an easy and dependable FTIR technique for their characterization. The results highlight the importance of theoretical predictions in improving the accuracy of FTIR peak assignments for MXenes.