Pure bentonite clay has been modified through acid thermal treatment (ATTB) and by pillaring with titania and vanadia (Ti-PILB and V-PILB). Iron (II) phthalocyanine complex (FePc) was immobilized in 0.5 wt% loading on the modified bentonite supports. Structural characteristics were investigated through XRD, FTIR and ICP-EDX techniques. Textural and morphological characteristics were estimated from adsorption-desorption isotherms of N-2, pore size distribution analysis and SEM. Dispersion parameters of FePc molecules were determined from H-2 chemisorption isotherms at 300 degrees C. Cation exchange capacities and acid-base behaviours were also studied. Incorporation of oriented FePc was found to reorganize the clay layer stacking, being deformed upon modification, through interaction with pillar (in V-PILB) or with interlayer sites (in Ti-PILB). Catalytic performance of different samples in in situ bulk polymerization of methyl methacrylate at 60 degrees C was discussed, where living polymerization mechanism, within the role of FePc in re-initiation of dormant polymer molecules, was confirmed. (M) over bar (w) and (M) over bar (n) of produced polymers decreased, according to the used support, in the order: Ti-PILB > ATTB>V-PILB, the same decreasing order of chain transfer constant (C-T), related to contribution of FePc. A new approach for synthesis of polymer/modified bentonite composites of partially exfoliated layers was provided. In PMMA/FePc/V-PILB composite, nanoclay particles (of 25 nm) were shown with more ordered polymer chains and well dispersed vanadia pillar species, in a strong interaction and high compatibility with FePc. (C) 2010 Elsevier B.V. All rights reserved.