The present invention provides a process for the preparation of Vanillin (4-hydroxy-3-methoxy benzaldehyde) by a single-step oxidation of ferulate moiety of rice straw, a renewable agricultural waste. This is a chemical method where vanillin is produced from a renewable resource in a single-step using a green oxidizing reagent and green solvent. Apart from that the water and the inorganic compounds can be recycled.