Fe(III) pillared montmorillonite samples have been prepared by intercalating trinuclear acetato hydroxy-iron (III) nitrate [Fe(COOCH3)(7)OH 2H(2)O](+) NO3- between the layers of both Na-exchanged and acid-activated montmorillonite, followed by calcination and characterized by various techniques. The multistep ion exchange process gave better complex loading than the single step process. FTIR and Mossbauer spectral analysis showed the presence of the complex inside the silicate layers. Materials prepared from the two starting materials are thermally stable up to 500 degrees C, having basal spacings of 18.0 and 17.6 Angstrom and high surface areas of 284 and 276 m(2)/g, respectively. The acid-activated pillared montmorillonite shows somewhat low complex intake, but has high acidity in comparison to the Na-exchanged material.