INTRODUCTION Physical properties of Methane Sulphoic Acid Methane sulphonic acid is a clear colourless liquid available as a 70% solution in water and anhydrous form. The structure of methane sulphonic acid lends itself to many catalytic reactions, due to its high acid strength (pKa= -1.9) and low molecular weight (96.0 g/mol). Methane Sulphonic Acid is Green Acid Catalysts i. It is easy to handle methane sulphonic acid as liquid and can be recyclized. ii. It has low LD 50 and biodegradable forming sulphate and CO 2 . iii. Methane sulphonic acid is considered to be ORIENTAL JOURNAL OF CHEMISTRY www.orientjchem.org An International Open Free Access, Peer Reviewed Research Journal ISSN: 0970-020 X CODEN: OJCHEG 2015, Vol. 31, No. (1): Pg. 447-451 Methane Sulphonic Acid is Green Catalyst in Organic Synthesis PRAMOD KULKARNI Department of Chemistry, Hutatma Rajguru Mahavidyalaya Rajgurunagar Pune - 410505, India. *Corresponding E-mail: pramodskulkarni3@gmail.com http://dx.doi.org/10.13005/ojc/310154 (Received: December 05, 2014; Accepted: January 10, 2015) ABSTRACT Methane sulphonic acid is an alkanesulphonic acid and its chemical formula is CH 3 SO 3 H. MSA is a strong acid having pKa= 1.9 and completely ionized in 0.1M in an aqueous solution and has small affinity to oxidize organic compounds, less corrosive and toxic than other mineral acids. MSA is also biodegradable and not evolve toxic gases. Therefore MSA is considered as green acid. Therefore its use in organic synthesis attracts many chemists to use in organic synthesis. In this review we described the MSA catalyzed organic transformation. Key words: Methane sulphonic acid, green, catalyst, organic reactions. natural product and is part of the natural sulphur. iv. It is less corrosive and toxic than other mineral acids. Due to these properties methane sulphonic acid making an environmentally benign material 1 . Applications of Methane sulphonic acid as catalyst in organic synthesis 1. H. Naeimi et. al used methane sulphonic acid as catalyst for regioselective route for Direct Ortho-Acylation of Phenols and Naphthols under Microwave condition 2 . 2. M. Heravi et. al use MSA as catalyst for One-