The research relevance is determined by the constant striving to improve and enhance sea buckthorn genotypes by using different genetic resources and breeding methods to achieve better adaptability, higher productivity, and fruit quality. The research aims to expand the genetic diversity of sea buckthorn, which combines high productivity and quality for further breeding. Phenology, morphological studies, and evaluation of breeding material for economically valuable traits were carried out according to the methodology for the examination of plant varieties, and molecular genetic studies – according to the polymerase chain reaction method, which is based on multiple copies of a specific DNA region. The formative process in sea buckthorn breeding for adaptability, productivity and quality was expanded by using the gene pool of related forms, which is one of the ways to solve the problems of creating source material for further breeding and is the basis of the research, which established a wide range of formative process by morphological traits and biological properties as a result of the hybridisation of biotypes, which allowed to select valuable hybrids for a set of breeding and, in particular, new forms of Soborna and Adaptyvna Improved were identified, characterised by high winter and drought resistance, productivity and fruit quality, absence of thorns and dry fruit separation, and submitted to the State Variety Testing. The obtained genotypes of sea buckthorn plants combine resistance to high and low environmental temperatures with a complex of other economic traits: disease resistance, low or no thorniness, fruit quality and their suitability for processing and production of products for healthy nutrition. The practical value of the study is based on the fact that the results of the research expand the information on the use of sea buckthorn adaptability, productivity, and quality in breeding, selected and studied in the natural and fallow ecosystems of Polissia and Forest-Steppe of Ukraine. As a result of the study, the best samples were selected and included in the Genetic Bank of Plants of Ukraine as material with valuable horticultural traits and involved in breeding work at the Institute of Horticulture of the National Academy of Agrarian Sciences of Ukraine