  We study symplectic structures on characteristically nilpotent Lie algebras
(CNLAs) by computing the cohomology space $H^2(\Lg,k)$ for certain Lie algebras
$\Lg$. Among these Lie algebras are filiform CNLAs of dimension $n\le 14$. It
turns out that there are many examples of CNLAs which admit a symplectic
structure. A generalization of a sympletic structure is an affine structure on
a Lie algebra.
