Combined use of rotational spectroscopy and ab initio calculations at the MP2/6-311++G(d,p) level of theory shows that the complex formed between vinyl fluoride and hydrogen fluoride has a planar geometry in which HF forms a hydrogen bond to the F atom of vinyl fluoride. With ϕ=the angle CF⋯H=121.4° assumed from the ab initio calculation, the distance r(FH)=1.892(14) Å and the angular deviation θ=18.7(15)° of the F⋯H–F nuclei from collinearity were obtained by fitting the principal moments of inertia of the two isotopomers C 2 H 3 F⋯HF and C 2 H 3 F⋯DF investigated.