This work analyses the possibility of conditioning graphite pieces (with a large proportion of pores of different sizes up to 100 mu m) with a metal coating of copper or nickel produced by electroless plating, with the aim of completely isolating the graphite from its surroundings. Electroless plating with copper results in a very large proportion of pores filled or covered, but a fraction of the pores remain in the graphite, which decreases with increasing thickness of metal deposit. Furthermore, the copper plating is permeable to liquids and consequently the graphite does not become completely isolated from the surrounding. The percentage of porosity filled or covered by nickel deposits is similar to copper, but they are not permeable to liquids, at least when the thickness is relatively high, and consequently the access of the liquids to the graphite is rather limited. However, when electroless plating with copper is followed by nickel deposition the graphite becomes isolated from the exterior.