The present invention discloses a photocatalytic process and methodology for the preparation of acetic acid by a hydrocarboxylation reaction of methanol using carbon dioxide under visible light irradiation. Importantly, the reaction occurred under ambient temperature and pressure condition using a readily available household LED lamp in the presence of a transition metal based molecular photocatalyst, homogeneous as well as supported to semiconductor support and a CO 2-philic solvent without adding any external electron and proton donors.