The infrared spectrum of 12C2HD has been studied using synchrotron radiation at the far-infrared beam line,Canadian Light Source, Saskatoon, Canada. The spectra were recorded at a resolution of 0.00096 cm 1 in the 60to 360 cm 1 range using a Bruker IFS 125 Fourier transform spectrometer. In total, 821 vibration rotation lineswere observed and assigned to the P(J), Q(J) and R(J) transitions of the 5 4 difference band and associatedhot bands with J00 up to 35 and ( 4þ 5) up to 3. These new transitions were analysed together with 4518transitions involving bending states with ( 4þ 5) up to 3 available in the literature. The spectroscopic parametersobtained from the fit reproduce 4909 transitions with a standard deviation of 0.00028 cm 1. The 5 4 bands of13CH12CD and 12CH13CD were also detected and analysed.