A massive search for chemical routes leading to methanol formation in gas phase has been conducted using computational chemistry, at the CBS-QB3 level of theory. The calculations were performed at five different temperatures (100, 80, 50, 20, and 10 K) and at three pressures (0.1, 0.01, and 0.001 atm) for each temperature. The search was focused on identifying reactions with the necessary features to be viable in the interstellar medium (ISM). A searching,strategy was applied to that purpose, which allowed to reduce an initial set of 678 possible reactions. to a subset of 11,chemical routes that are,recommended, for the first time, as potential candidates: for :contributing to methanol formation in the gas phase of the ISM. They are all,barrier-less, and thus they are expected to, take place at,collision rate Hopefully, including these reactions in. the currently available models, for the gas phase methanol formation in the ISM, would help improving the predicted fractional abundance of this Molecule,in dark clouds. Further investigations, especially those dealing with grain chemistry and electronic excited states, would be Crucial to get a complete picture of the methanol formation in the ISM.