A series of iron oxide nanocatalysts were prepared using an ultrasonically assisted co-precipitation technique. Molybdenum promoted Fe3O4 and Fe2O3 were prepared from the original materials by wet impregnation using a solution of ammonium molybdate. The catalysts were tested in the liquid phase oxidation of benzene at atmospheric pressure and at 60°C using molecular oxygen. Phenol yields between 7% and 14.5% were obtained. The major products were pyrogallol and catechol.