Radosław Zaleski is a specialist in positron annihilation. He graduated in physics from the Maria Curie Skłodowska University in 2000, where he obtained a doctoral degree in 2005 and habilitation in 2014. In the years 2000-2005, he was working on the development of an extended model of positronium annihilation, its implementation in a computer code, experimental verification, and various studies related to porous materials. The model allowed for the extension of the applicability of positron annihilation lifetime spectroscopy to the characterization of mesoporous materials in vacuum and its further modification in air. Among his studies, in-situ studies of the processes taking place in the mesopores observed with a microscopic positron probe were particularly interesting: thermal decomposition, adsorption, phase behavior of confined substances, experimental measurement of negative pressure under concave meniscus, etc. His important discovery is an experimental detection of breaking hydrogen bonds in water under high negative pressure in nanometer-sized capillaries. In parallel, he deals with the fundamental issues of positron and positronium and organic materials, as well as applied research on the strengthening of the surface layer of construction materials, food processing, drug delivery, positron emission tomography, and material science. He specializes in positron annihilation lifetime spectroscopy but is also proficient in various material characterization techniques.