Nickel pentacyanonitrosylferrate (NiPCNF) films have been deposited on the surface of an aluminum electrode by a simple electroless dipping method. The cyclic voltammogram of the resulting surface modified Al electrode prepared under optimum conditions, shows a well-behaved redox couple due to the [(NiFeIII/II)-Fe-II(CN)(5)NO](0/ -1) system. The NiPCNF films, formed on the Al electrode show excellent electrocatalytic activity towards the oxidation of ascorbic acid in phosphate buffer solution of pH 7.2. A linear calibration graph is obtained over the ascorbic acid concentration range 2-50 mM using linear sweep voltammetry. The kinetics of the catalytic reaction were investigated using cyclic voltammetry, rotating disk electrode (RDE) voltammetry and chronoamperometry. The results were explained using the theory of electrocatalytic reactions: at chemically modified electrodes. The rate constants for the catalytic reaction evaluated by three different approaches, are in good agreement and were found to be around 10(-3) cm s(-1). Further examination of the modified electrodes shows that the modifying layers (NiPCNF) on the aluminum substrate have reproducible behavior and a high level of stability.