Nano-structured iron molybdate materials, comprising Fe-2(MoO4)(3) nano-particles anchored onto MoO3 nano-rods, have been synthesised and evaluated as catalysts for the selective oxidation of methanol to formaldehyde. The catalysts were benchmarked against a standard iron molybdate catalyst prepared by co-precipitation and were found to have comparable performance under the test reaction conditions. The materials have been characterised using a combination of electron microscopy, powder X-ray diffraction and Raman spectroscopy. The synthesised MoO3 nano-rods were found to have a uniform structure, 8-10 mu m in length with a rectangular cross-section of 50-100 nm x 100-200 nm. Fe was impregnated onto the MoO3 nano-rods via incipient wetness with an aqueous solution of Fe(NO3)(3)center dot 9H(2)O. Calcination of these precursors formed 20-200 nm Fe-2(MoO4)(3) islands on the surface of the nano-rods via a solid-state diffusion mechanism, and the size of the Fe-2(MoO4)(3) islands could be controlled by varying the Fe loading. The effect of the temperature and duration of calcination were investigated, and it was found that the optimum conditions were 450-500 degrees C for 2 h. At 350 degrees C, the temperature was too low for the solid-state reaction between the MoO3 nano-rod and the surface Fe to occur, and no Fe-2(MoO4)(3) was formed. At higher temperatures, the nano-rod morphology was compromised, and irregular, partially coalesced particles of Fe-2(MoO4)(3) were generated, which had a lower catalytic performance than the nano-structured Fe-2(MoO4)(3)/MoO3 materials. At 400 degrees C, the solid-state reaction occurred sufficiently slowly for mechanistic aspects of the Fe-2(MoO4)(3) island formation to be elucidated by transmission electron microscopy. (C) 2012 Elsevier Inc. All rights reserved.