The contribution of Professor Georgy De-Metz to the development of physical science in Ukraine is highlighted. The information about the childhood of the future scientist is given and his formation as a scientist is shown. He was extensively involved in physics under the guidance of F. Shvedov and M. Umov. The head of his master’s thesis was Professor A. Kundt. After the publication of the discovery of X-rays by Roentgen, G. De-Metz not only repeated the experiments of the German colleague, but also put new ones. In particular, he investigated the influence of various physical factors on obtaining the clear photographs of this radiation. The scientist managed to make clear pictures of frogs with an image of the internal organs. He also explored the possibility of using X-rays in medicine. In the early twentieth century, he published his first major work on radioactivity “Doctrine of the radioactivity and radioactive substances”, in which the scientist described the physical basics of radioactivity in detail. The researcher examined the radium content in water and flora from the pond of the Kyiv Botanical garden. Using the results of the studies G. De-Metz concluded that some types of living tissue were able to absorb and even concentrate radium from water and the environment. In his work “Radioactivity and the structure of matter,” not only a historical review of the development of the doctrine of radioactivity was made, but also the new experimental works of the author were represented. He analyzed 68 various minerals of uranium. G. De-Metz described the picture of the geographical distribution of radioactive minerals and identified the richest deposits of uranium ore at that time. In addition to his scientific work, the scientist was a well-known methodist. It was he who, in the 1920s, developed a method of teaching physics in institutes of Ukraine. It is reported that the scientist in a different period of time was the head of the physical department at various institutions of higher education. Moreover, he was even the Rector of the St. Volodymyr University, Kyiv Polytechnic Institute, and Kuban University.