Authors Dieter Degrijse, Nansen Petrosyan Title On cohomology of split Lie algebra extensions Abstract We introduce the notion of compatible actions in the context of split extensions of finite dimensional Lie algebras over a field. Using compatible actions, we construct a new resolution to compute the cohomology of semi-direct products of Lie algebras. We also give an alternative way to construct the Hochschild-Serre spectral sequence associated to a split extension of finite dimensional Lie algebras and obtain a sharper bound for the length of this spectral sequence. Status Journal of Lie Theory, 22 (1) (2012), 1-15