Two catalysts prepared separately by iron pillaring of two different-sized particle fractions of a dried, ground and sieved clay mineral were tested for catalytic performance in photo-Fenton discoloration of methylene blue aqueous solutions. Two different-sized particle fractions of the mineral were selected prior to pillaring, ranging below 250 mu m and within the range of 250450 mu m, respectively. The resulting solids were characterized by thermogravimetric analysis, nitrogen adsorption isotherms and ultimate analysis at different preparation stages. Significant differences were found in catalyst textural parameters according to the starting mineral particle size, a higher specific surface area, and specific pore volume, was found for the catalyst obtained from the smaller-sized particle fraction of the mineral. Both catalysts showed activity in the discoloration of aqueous dye solution. Differences in catalyst performance were correlated with textural parameters. Trial tests were conducted in different experimental conditions, enabling the assessment of contributions of different catalytic mechanisms. (C) 2008 Elsevier B.V. All rights reserved.