Oxidation reaction of indole to isatin was performed in the presence of Fe3O4 nanoparticles (as catalyst) and commercial grade perhydrol (as oxidant). Magnetite nanoparticles were synthesized via chemical precipitation method and characterized by XRD and TEM techniques. The efficiency of reaction was obtained from GC analysis of the mixture. The catalyst was easily separated from the reaction mixture (after completion or before each injection) by using a
magnetic field of 1.4 T. The recycled catalyst maintained activity for successive runs.