Application of conventional methods of dilatational surface rheology in combination with optical techniques and atomic force microscopy allowed determination of the surface properties of a water-soluble fullerene derivative, carboxyfullerene C60(C(COOH)2)3. It has been shown that the surface activity of this derivative is higher than that of other soluble fullerene derivatives, for example, of fullerenols. The dynamic surface elasticity of carboxyfullerene solutions reaches up to values of about 180 mN/m. Brewster angle microscopy indicates a liquid-like nature of carboxyfullerene adsorption layers. The application of atomic force microscopy shows that these adsorption layers consist of numerous interconnected surface aggregates. The size and number of aggregates increase during adsorption. The compression of carboxyfullerene spread layers results in its partial dissolution. At the same time, the compression isotherms indicate a high stability of the layers of carboxyfullerene aggregates.