For oil and gas offshore production, any extension of the Multiphase Production Concept to more complex effluents under more difficult transport conditions, requests a better understanding and control of (a) the thermodynamic behaviour of water-hydrocarbon mixtures, (b) the efficiency of Various additives (or mixtures of additives), necessary for a safe, reliable and economical operation of the production and transport facilities. One of the main additives used for hydrate control being methanol, this paper deals specifically with its thermodynamic properties and includes: (a) first, an exhaustive bibliography of experimental-data with the method used for the selection of a coherent and reliable data base, (b) then, a comparison of the results obtained, after adjustement on the data base: with various cubic and not-cubic equations of state: Peng-Robinson, Cubic-Chain-Of-Rotators (CCOR), Chain-Of-Rotators (COR), as well as with equations of state including methanol association phenomena (Anderko model, Wenzel and Krop model), (c) and finally, an empirical Bipolynomial equation of state which represents the methanol thermodynamic properties with a good accuracy.