1,1,1,2-Tetrafluoroethane dimer was investigated by pulsed jet Fourier transform microwave spectroscopy. One conformer, stabilized through a network of four C-H···F-C interactions, was observed, although several almost isoenergetic configurations were suggested by ab initio calculations. The measurements, extended to four 13C species in natural abundance, allowed determination of the carbon skeleton structures and evaluation of the weak hydrogen bond parameters. Information on the dissociation energy is also provided.