A vicinal Si(111) surface covered with a sub-monolayer amount of Au has been studied by reflection high energy electron diffraction (RHEED). At the coverage equal to 0.20 ML of Au, the RHEED pattern showed a reconstruction in the form of regularly distributed monoatomic steps. In order to determine the shape of the surface unit cell, several RHEED patterns obtained within a wide range of the electron incident angle were recorded and analyzed. The surface was composed of flat Si(111) terraces separated by single Si(111) steps. This surface was identified as an ideal Si(755) facet with Au atoms that form quasi-one-dimensional chains running along a Si[1(1) over bar0$] azimuth. Regularly spaced steps were stable within the investigated range of temperatures from 100 to 470 K.