As derived from silicon substrate, meso-porous Si could be a competitive candidate for many thermoelectric applications for micro-systems namely due to the huge decrease of its intrinsic thermal conductivity. As reported in the literature, this can offer a higher figure of merit as well as a more significant efficiency for energy harvesting at the microscale level at room temperature. Also, to consider the electronic transport that is lowered by the fabrication process, a graphenisation step is investigated both on the structural and thermoelectric behavior of the mesoporous complex Si matrix. Porous silicon membrane is obtained by electrochemical etching process from an electrolytic solution of hydrofluoric acid and ethanol. Depending on numerous parameters (porosity, pore size distribution, porous thickness...) the Seebeck coefficient has been investigated accordingly to key process parameters and correlated to the membrane morphology and structural characteristics. Using a new home-made thermoelectric device specifically designed for porous membranes will make possible to evaluate the Seebeck coefficient in the range of 10 to 70 °C. Systematic investigation of graphenized and non-graphenized membranes is conducted to determine the contribution of the graphene in the enhancement of the thermoelectric properties. In parallel, electrical measurements (Van Der Pauw and Hall effect techniques) and thermal characterization (Pulsed photothermal and pulsed electrothermal methods) are also achieved for the estimation of the ZT coefficient (thermoelectric performance of a material and depends on the σ, electrical and k, thermal conductivity and S, the Seebeck coefficient) and the power factor (given by σS2).