It is shown that the non-trivial cocycles on simple Lie algebras may b
e used to introduce antisymmetric multibrackets which lead to higher-o
rder Lie algebras, the definition of which is given. Their generalised
Jacobi identities turn out to be satisfied by the antisymmetric tenso
rs (or higher-order ''structure constants'') which characterise the Li
e algebra cocycles. This analysis allows us to present a classificatio
n of the higher-order simple Lie algebras as well as a constructive pr
ocedure for them. Our results are synthesised by the introduction of a
single, complete BRST operator associated with each simple algebra.