Porous materials have attracted the attention of chemists due to their various applications such as heterogeneous catalysis, chemical separations via adsorption. Macroporous transition metal oxides viz. CuO, NiO, CoO, Mn2O3, Cr2O3 and ZnO were synthesized and used as an efficient, heterogeneous, reusable and eco-friendly catalyst for four different organic transformations viz. N-formylation, N-acylation, O-acylation and Friedel Craft acylation under solvent-free conditions in good yields. These results were compared with the literature. © 2007 Elsevier B.V. All rights reserved.