The oxymercuration reaction is a chemical reaction used in organic chemistry to form a neutral alcohol without any rearrangement of carbocations. In this reaction, similar to some other organic reactions, the Hg2+ ion works to stabilize the molecule to prevent carbocation formation and so prevents rearrangement. The reaction results in a product that follows Markovnikov's rule.

The general equation for the reaction is as follows:

C=C in H2O / THF with Hg(OAc)2, and then with NaBH4, --> HO-C-C-H