Positronium Chemistry focuses on the methodologies, reactions, processes, and transformations involved in positronium chemistry. The publication first offers information on positrons and positronium and experimental methods, including mesonic atoms, angular correlation measurements, annihilation spectra, and statistical errors in delayed coincidence measurements. The text then ponders on positrons in gases and solids. The manuscript takes a look at the theoretical chemistry of positronium and positronium chemistry in gases. Topics include quenching, annihilation spectrum, delayed coincidence method, rate of two-photon and three-photon annihilations, and angular correlation of two-photon distribution. The book also considers positronium chemistry in the condensed state, as well as liquid gases, organic solids, and aqueous solutions. The publication is a primary reference for chemists and readers interested in positronium chemistry.