The v4 band of 1,1,1-trifluoroethane (CH3CF3) has been studied using synchrotron radiation at the far-infraredbeamline, Canadian Light Source. The spectra were recorded at a resolution of 0.00096cm1 in the spectralrange 800 to 860cm1 using a Bruker IFS125 FT spectrometer. Altogether 2785 lines were assigned to qPK(J )and qRK(J ) transitions with J 00 up to 71 and K up to 45. The qQK(J ) sub-branches are too congested andoverlapped to other hot-band Q branches to be analysed. A Watson-type Hamiltonian containing the usual termsup to the 6th power in the angular momentum operators was used in the analysis. The spectroscopic parametersobtained from the fit reproduce 2636 transitions with a standard deviation of about 0.00016cm1.