In this paper, we present results from molecular dynamic simulations devoted to the characterization of the interaction between water molecules and a soot Surface modeled by the anchoring of COOH groups on the face side of a graphite surface. The molecular dynamics simulations are based on a classical potential issued from quantum chemical calculations. They provide a view of the dynamics and the structure of water clusters on the model soot surface at 250 K The results of these simulations show that the COOH groups act as strong trapping sites for a few water molecules that then become nucleation centers for other water molecules that form larger aggregates tied to the COOK They show also that water adsorption on a model soot surface depends on the type, the number, and the relative positions of active sites on the surface.