The structure of the proton conducting phase of Rb3H(SeO4)(2) has been investigated by means of single crystal neutron diffraction experiments at 470 K. Difference Fourier maps of scattering densities and the application of different models to localize the positions of the light atoms, allow a detailed determination of the structure including the proton subsystem. Evidence for different motions of the hydrogen atoms reveal new aspects of the mechanism of proton conduction.