Prof. dr hab. Paweł Kowalczyk is employed as a professor at the Faculty of Physics of the University of Warsaw. His research is concentrated around laser spectroscopy of diatomic molecules. After several scholarships in Germany, Canada and France he initiated experimental studies of molecular spectra in Warsaw, employing an original method of polarization labelling spectroscopy and specializing in spectroscopy of alkali metal dimers. During thirty years of intensive research he studied more than 90 electronic states of these molecules. In recent years he concentrates his research on such states which are important in processes of formation of ultracold molecules from laser cooled atoms, being a hot topic in contemporary experimental physics. At the same time he develops methods of description of observed molecular states, in particular the method of pointwise Inverted Perturbation Approach. At present this is the only method allowing to construct potential energy curves of „exotic” shapes common among excited electronic states (potentials with double minima, internal barriers etc.) and as such it is employed by many research groups in the world. Professor Kowalczyk was a deputy director of the Institute of Experimental Physics in the years 2008-2016 and from 2016 is the director of the Institute.