This project is aimed at theoretical and experimental studies of the Bose-Einstein Condensation (BEC) of exciton-polaritons in photonic microstructures, which provide two-dimensional or three-dimensional localization of light such as microdiscs, microspheres, cylindrical and spherical Bragg microcavities, and microcavities based on photonic crystals. For this purpose we will: 1) Calculate eigenmode spectrum for photonic microstructures in the case of bare optical modes and for exciton-polaritons. 2) Derive the conditions for the weak coupling-strong coupling threshold for each type of the photonic microstructure. 3) Obtain phase diagrams for exciton-polariton 4) Develop a theory for the exciton-polariton interaction with phonons in the above mentioned photonic microstructures, and analyse the relaxation mechanisms, and develop a technique for the qualitative description of polariton relaxation. 5) Analyse BEC in microstructures based on various materials, and particularly wide band gap semiconductors with large electron binding energy such as GaN and ZnO. 6) Provide modelling and a physical understanding of experimental results related to this proposal. 7) Analyze the condition of formation of BEC of exciton-polariton under the electrical injection of carriers. 8) Produce a technical specification for a realistic room-temperature polariton laser. 9) Investigate spin-related phenomena in polariton condensate in novel types of microcavities. 10) Analyse the possibility of electrical pumping of polariton devices based on photonic microstructures. 11) Produce prototypes of polariton laser operating at room temperature under electrical pumping and investigate them experimentally.