In this paper, we study the electronic properties of CoSi2 metallic islands grown on a Si(100) surface with a low-temperature (9 K) scanning tunneling microscope (STM). The atomic scale structures of the flat and ridge silicide islands surfaces are described with an ultimate resolution, thanks to the stability of low-temperature STM. A statistical study of the I–V and dI/dV signals acquired along the islands shows their metallic-like properties and a very small residual conduction band gap of ∼30 mV. This reveals that the electronic transport through the individual metallic islands at the silicide–silicon interface is mainly ruled by electronic tunnel processes for positive sample biases and driven by the presence of gap states for negative sample voltage. The role of the gap states is demonstrated by performing conductance measurements along the dimer vacancy lines in which interstitial Co atoms are accessible at the silicon surface. Hence, the electronic transport that occurs from the silicide–silicon interface toward the macroscopic contact of the sample can be explained.