Previously reported size dependent maximum in self diffusivity D of a sorbate confined to zeolite faujasite has been analysed to understand the nature of the third regime where the sorbate diameter is comparable to the void diameter. In the third regime self diffusivity decreases rapidly with increase in sorbate diameter.Activation energy of the particles in regime III is comparable to those in regime It rather than regime I suggesting that the region III should be classified as belonging to regime II (also known as the anomalous regime) rather than regime I (the linar regime) where D proportional to 1/sigma(gg)(2), sigma(gg) being the sorbate diameter. (C) 2004 Elsevier B.V. All rights reserved.