We study the class K2 + K4 of homogeneous pseudo-Kähler structures in the strongly degenerate case. The local form and the holonomy of a pseudo-Kähler manifold admitting such a structure is obtained, leading to a possible complex generalization of homogeneous plane waves. The same question is tackled in the case of pseudo-hyper-Kähler and pseudoquaternion Kähler manifolds.MSC2010: Primary 53C30, Secondary 53C50, 53C55, 53C80. Key words and phrases: homogeneous plane waves, pseudo-hyper-Kähler, pseudo-Kähler, pseudo-quaternion Kähler, reductive homogeneous pseudo-Riemannian spaces. stance), the so-called homogeneous structures of linear type characterize negative constant sectional (holomorphic sectional, quaternionic sectional) curvature (see [9], [17] and [27] for these results as well as indications of other similar results). When the case of metrics with signature is analyzed, the causal nature of the vector fields characterizing a homogeneous structure of linear type gives rise to different scenarios with some physical implications. In [23] and [24] the purely pseudo-Riemannian case with an isotropic structure is studied in full detail: More precisely, it is proved that these spaces have the underlying geometry of a real singular homogeneous plane wave. The aim of this paper is to extend this result to the pseudo-Kähler, pseudo-hyper-Kähler and pseudo-quaternion Kähler settings.The main characterization of this work gives the geometry of pseudo-Kähler manifolds with a so called strongly degenerate homogeneous pseudo-Kähler structure of linear type. In particular, the expression of the metric obtained in the characterization has strong similarities with singular scale-invariant homogeneous plane waves. Furthermore, the manifolds under study and these homogeneous plane waves share some other analogies and features as it is shown in §5. Because of this, since there is not a formal definition of "complex plane wave" (as far as the authors know), pseudo-Kähler manifolds with strongly degenerate linear homogeneous structures seem to be the correct generalization of this special kind of homogeneous plane waves in complex framework, at least in the important particular Kähler case. In addition, the same techniques are successfully applied to a comparison of Cahen-Wallach spaces and one of the possible pseudo-Kähler symmetric spaces of index 2 in the classification given in [19], giving a more general picture of complex plane waves.A relevant fact about these spaces is that they have holonomy group contained in SU (p, q). Consequently, it is natural to study strongly degenerate homogeneous pseudo-hyper-Kähler and pseudo-quaternion Kähler structures of linear type. However, we prove that a manifold admitting any of those structures is necessarily flat, pointing out that the notion of homogeneous plane wave can not be realized in the pseudo-hyper-kähler or pseudo-quaternion Kähler cases in a non-trivial way.The paper is organized as follows. In Section 2 we recall some results concerning homogeneous pseudo-Riemannian s...