Sulfur dioxide (SO2) is not only a useful building block in a synthetic organic chemistry, but in its liquid state can be used as a strong polar solvent as well. Besides, liquid SO2 is one of the few polar solvents that possess Lewis acid properties. On the other hand, synthesis of both ketones and α-vinyl halides from alkynes can be facilitated by additive of Lewis acid and both transformations may proceed through vinyl cation intermediate. Herein we report novel conditions for catalytic alkyne hydration and a new approach for the alkyne hydrohalogenation promoted by liquid SO2 as a reaction medium.