Green route synthesis of iron oxide nanoparticles (IONPs) was successfully carried out using leaf extract of Ocimum tenuiflorum (Ram Tulsi variety). The synthesis method employed was found to be easy and made use of simple precursors. The IONPs thus formed were magnetic in nature and easily recovered from the solution. Preliminary characterization of the synthesized IONPs was carried out using UV-Visible spectroscopy. The spectrum exhibited characteristic absorption peak at 282 nm corresponding to magnetite (Fe3 O4 ). FTIR spectrum showed formation of IONPs with distinct absorption bands assigned to the Fe-O bond stretching. XRD spectrum confirmed formation of magnetite along with α-Fe2 O3 . Further studies using TEM indicated presence of nanospheres and nanoellipsoids. Nanospheres were found to range from 3-5 nm and nanoellipsoids were of the dimensions of 100-200 nm in length and 20-30 nm in diameter. The dye degradation capacity of the synthesized IONPs revealed high reactivity and efficiency of dye removal showing their potential as nanocatalysts. The synthesis method reported here was found to generate two different phases of IONPs viz. magnetite (Fe3 O4 ) and hematite (α-Fe2 O3 ) both of which possess important biomedical and environmental applications.