In orbit, satellites are exposed to significant thermal variations. To ensure reliable operation of their on-board systems and equipment, a thermal control of the spacecraft is necessary using cold, neutral or warm coatings. The Materials and Coatings Laboratory of the Thermal Control Services at CNES has elaborated a cold coating version by using a polysiloxane deposit on a metal substrate (such as polished aluminum or vacuum deposited silver). In geostationary orbit, polysiloxane, which has a high electrical resistivity (>10(17) Omega m), can accumulate implanted charges that can give rise to electrostatic discharges and damage the neighboring electronic systems. To prevent any electrostatic discharge problems in geostationary orbit, the resistivity of coatings should be reduced without altering their thermo-optical properties, in particular the low solar absorptivity and the high emissivity for cold coatings. Several methods have been studied, such as the incorporation of carbon nanotubes (CNT) and indium tin oxide (ITO) nanoparticles in the polysiloxane matrix, with the objective of attaining a high transparency, a high emissive, and an antistatic resin. In this paper, the influence on thermo-optical properties of CNT-Polysiloxane and ITO-Polysiloxane composites, as a function of sample thickness d (mu m) and nanoparticles concentration p (%wt), is reported.