The microporosity of H-MCM-22 samples, fresh and deactivated by coke during methylcyclohexane transformation at 350 C for 10 h, was characterised by adsorption of nitrogen and organic molecules of different size, namely, p- and o-xylenes, mesitylene and methylcyclohexane. Nitrogen adsorption was also carried out on the fresh sample after pre-adsorption of the hydrocarbons. All of these can fit the outer 12 MR c...