The monograph considers one of the most extensive classes of nanostructured polymers - polyaniline as well as methods for obtaining it and numerous applications. Forms are described in which polyaniline can exist depending on the state of oxidation and doping, i. e. the content of oxidized nitrogen atoms and their interaction with acids. The greatest attention is paid to the average degree of PANI oxidation by the most stable emeraldine form which can exist in a doped conductive and doped non-conducting state. The possibility of controlling the morphology of a polymer and changing the structure of a film from a monolayer of close-packed spherical particles to loose layers assembled from one-dimensional particles with different forms of their organization is substantiated. Based on the author's experience with nanoscale polymer particles and in accordance with modern scientific achievements, data on the structure of materials based on polyaniline are systematized. Data on the methods of polymer morphology management, on potential areas of its use in modern engineering, and electronics are generalized.