Hydroboration-Oxidation is a two-step procedure that converts alkenes into alcohols.

1. Hydroboration: Borane ($B{H}_3$ or $B_2{H}_6$) adds across the double bond.
2. Oxidation: The organoborane is oxidized using alkaline Hydrogen peroxide ($H_2{O}_2,O{H}^{-}$).

• Regioselectivity: The overall result is the addition of water across the double bond in an Anti-Markovnikov sense ($OH$ adds to the less hindered carbon).
• Stereochemistry: It is a Syn-addition, where $H$ and $OH$ add to the same face of the alkene.