The Lorentz self-broadening (halfwidths) and self-induced pressure-shift coefficients were measured for the first time in the octadregion of methane. All spectra were recorded at 0.011 cm 1 resolution using the McMath–Pierce Fourier transform spectrometerlocated at the National Solar Observatory on Kitt Peak, Arizona. 12C-enriched CH4 gas samples at room temperature were used,and high signal-to-noise ratios of 2000:1 were achieved. The multispectrum nonlinear least squares fitting technique enabled us to fitsimultaneously a total of 10 high-resolution laboratory absorption spectra consisting of six self-broadened and four air-broadenedspectra. In this paper, we report the self-broadened widths and self-induced pressure shift coefficients for 1423 transitions belongingto five bands with a maximum J of 16. The numbers of measurements by bands are: 71 for m2 + 2m4, 202 for m1 + m4, 824 for m3 + m4,58 for 2m2 + m4, and 268 for m2 + m3. The observed widths varied from 0.045 to about 0.090 cm 1 atm 1 at 296 K. The measuredpressure-shift coefficients had values extending from about 0.020 to 0.005 cm 1 atm 1 at 298.3 ± 1.2 K. The results obtainedfor the broadening coefficients in the various bands were compared with each other and with measurements reported in the literaturefor other methane bands. 2005 Elsevier Inc. All rights reserved.