  Topological conformal field theories based on superconformal current algebras
are constructed. The models thus obtained are the supersymmetric version of the
$G/G$ coset theories. Their topological conformal algebra is generated by
operators of dimensions $1$, $2$ and $3$ and can be regarded as an extension of
the twisted $N=2$ superconformal algebra. These models possess an extended
supersymmetry whose generators are exact in the topological BRST cohomology.
