Using a tunable diode-laser spectrometer, we have measured the CO2-broadening coefficients of 28 absorption lines in the ν4ν4 band of CH4. Each line was recorded at room temperature (296 K) and at 4 different pressures, ranging from 8 to 50 mbar. The experimental determination of the CO2-broadening coefficients was performed by fitting a theoretical profile to the experimental profile of each line recorded at each pressure. Voigt, Rautian–Sobel’man and Galatry models were therefore used. The impact of these determinations on atmospheric investigations on CO2-rich planetary atmospheres are addressed.