  Extended Drinfel'd algebra (ExDA) is the underlying symmetry of non-Abelian
duality in the low-energy effective theory of string theory. Non-Abelian
U-dualities in maximal supergravities have been studied well, but there has
been no study on non-Abelian dualities in half-maximal supergravities. In this
paper, we construct the ExDA for half-maximal supergravities in $d\geq 4$. We
also find an extension of the homogeneous classical Yang-Baxter equation in
these theories.
