As electroactive molecules, polyoxometalates (POMs) have potential in charge trapping or resistive molecular memories, yet scarcely investigated until very recently. Since charge/discharge processes as well as transport properties are dependent upon the organization of the thin layers, we chose to explore a covalent approach and we prepared a diazonium post-functionalized Keggin-type polyoxometalate [PW 11 O 39 {Ge(p-C 6 H 4-CC-C 6 H 4-N 2 +)}] 3-that was subsequently anchored on hydrogenated n-type Si(100) surfaces. A flat and homogeneous hybrid POM monolayer is obtained and characterized by AFM, ellipsometry and XPS techniques. Vertical and lateral electron transfers are studied by cyclic voltammetry and scanning electrochemical microscopy (SECM). If the electron transfer between the POM layer and the silicon surface is quite slow (k ETvert = 5 s-1), SECM suggests that the monolayer displays a good lateral conductivity. Interestingly, SECM experiments evidence the influence of the organization of the layer on the lateral charge transfer and show the possibility to accumulate negative charges within the POM monolayer.