Fractal dimension of a thin-film of An deposited on the liquid\liquid interface generated between 4-methyl-2-pentanone and aqueous solution was determined. The An film was electrochemically deposited on the interface using an interfacial deposition method. In the specified experimental conditions employed, the electrodeposition provides an An film with uniform surface structure, and the fractal dimension of the An film can be considered as a factor of the interface structure. Thus, an electrochemical method, based on the time-dependency of the diffusion-limited current after a potential step, was applied for determination of the fractal dimension of the An film deposited on the liquid\liquid interface. The validity of the results were examined by determining the fractal dimension of the An film deposited on the liquid\liquid interface using another technique viz. cyclic voltammetry. There was a good agreement between the results obtained from different methods. Similar approaches were also employed for fractal study of an An film deposited on a liquid\gas interface, i.e. between an aqueous solution and air. (C) 2003 Elsevier B.V. All rights reserved.