Platinum electroless deposition on silicon from HF solutions was studied by scanning electron microscopy and transmission electron microscopy, focusing the interest on the different evolution of the deposit on n- and p-doped samples. In both cases the final result was that a complete platinum layer was eventually formed, but the process was hindered on n(+) substrates which exhibited an induction period and displayed a more local behavior compared to p substrates. The results are discussed in terms of a global electrochemical process in which silicon is oxidized and platinum reduces injecting holes to the silicon valence band.