The results of an investigation into the liquid structure of fluorosulfuric acid measured using neutron diffraction with isotopic substitution are reported. The first-order neutron difference function is extracted from data recorded at 300 and 193 K from isotopically labeled FSO3H and FSO3D. Analysis of the derived radial distribution functions shows that unique, multisite hydrogen bonding is present in the liquid. These results suggest hydrogen bonding between the hydrogen and fluorine as well as oxygen occurs in the liquid. The fraction of molecules that is hydrogen bound in each way varies with temperature, with the 193 K data showing a more tightly bound system.