It depends on the nature of the alkyne.
The usual procedure doesn't work with alkynes, but you can modify the conditions.
The modified conditions
You use catalytic amounts of
Reaction with internal alkynes
Internal alkynes give α-diketones.
Reaction with terminal alkynes
Terminal alkynes give a carboxylic acid with one less carbon atom.
In each case, the reaction is behaving as if it forms a 1,1,2,2-tetraol (the diketone dihydrate), which then loses water in the usual way.