We have investigated sub-monolayer coverages of Sn on the Ag/Ge(111) 3×3 surface. It was found that ≈0.45 monolayer (ML) resulted in a new, well-defined, reconstruction with a 33×33 periodicity. The periodic structure of the surface atoms was verified by low-energy electron diffraction and scanning tunneling microscopy. The electronic structure was studied in detail using angle-resolved photoelectron spectroscopy and core level spectroscopy at a temperature of 100K. Several surface bands were identified and their dispersions are presented along the Γ¯−M¯−Γ¯ and Γ¯−K¯−M¯ high symmetry lines of the 33×33 surface Brillouin zone (SBZ). The 33×33 surface has a metallic character since there is a strong surface band crossing the Fermi level near Γ¯ points coinciding with K¯ points of the 1×1 SBZ. The Fermi contour of the metallic band showed a hexagonal shape in contrast to the circular shaped Fermi contour of the initial 3×3 surface. Both empty and filled state STM images showed a hexagonal arrangement of protrusions with a local 3×3 periodicity and a superimposed modulation of the apparent heights resulting in a 33×33 periodicity.