The Duat as a regeneration dialectic space: In-habiting and re-signification of funerary space in the Underworld Books of the New Kingdom. This work is framed on the history of religious ideas of ancient Egypt, but, more precisely, on the funerary literature of the New Kingdom. Then, and specifically, it is framed on questions derived from its temporary nature, spatiality and its divine interrelationshA between Re and Osiris in the context of the nocturnal voyage of the sun by the world of the dead. The whole textual aim of the study, the Underworld Books, (the Book of Amduat, the Book of Gates, the Book of Caverns and the Book of the Earth) cosmogonic image by the reproduction of the sun journey during the night- and from which we will move forward inthe comprehensive analysis of the process we denominate of in-habiting between the gods Re and Osiris, resize not only the concept, by enriching it at an exponential way, but also the functionality, the dynamic and general structure of that space -dwAt- originally undetermined. The new layout I propose is a resizing of the funerary spaces, supported by the expansion and/or projection of the dwAt with an evolving and factual diversity as to subsume the other spaces that originally made up the hereafter in a broad sense -Axt, nwn and nwt-. I call this process duatization of the funerary space since we understand that in the Books of the Underworld it is emphasized the contraction of those three spaces from the expansion of the other -dwAt-, which ostensibly monopolises and functionally gathers the previous three. Regarding the interrelationshA issue between Re and Osiris, it is necessary to deep in the analysis of a divine link between two deities that represent supplementary functions, and that, not being conveniently included in the scope of syncretism and its variants (assimilation, co-habitation, identification, etc.), it is presented to us insufficiently encompassed as well as explained.