Topicality. Ukraine's economy should become high-tech, with a high level of wages and new requirements for the professional education system, with a high level of labor productivity based on automation, digitization and new management systems, with high-quality modern workplaces and working conditions. That is why this research is important and is to determine the essence of the technological core of the processing industry and methodological principles for assessing the technological level of development of its branches.Many scientific studies by foreign and domestic scientists have been devoted to the question of the essence research of the high-tech sector of the processing industry and the methodological principles of its assessment. The definition of the high-tech sector of the manufacturing industry as a set of industries in which a relatively high proportion of their income is spent on research and development has received the most widespread recognition. The definition of the high-tech sector of the processing industry as a set of industries in which a relatively high share of their income is spent on research and development does not reflect the multifaceted nature of this category, because it limits the understanding of the factors that determine the technological level of industries.Aim and tasks. To develop the conceptual principles of the essence of the high-tech sector of the processing industry and the methodological principles of assessing its technological level in the context of capitalization.Materials and methods. General scientific and special research methods were used in the work: comparison, generalization, synthesis, system analysis, logical-dialectical analysis, and others. The information base of the research include monographs, special literature, informational and analytical materials, domestic and foreign periodicals, data of the State Statistics Committee. Research results. Mechanical engineering is traditionally considered as the technological core of the processing industry. This is the most complex and differentiated part of the processing industry, which produces machines and machines, devices and aggregates, various mechanisms for industrial, household and military purposes, and for scientific research. Mechanical engineering determines the development of other branches of industry. In addition, it is an important factor in creating new jobs, raising people's living standards and ensuring the economic development of countries.Many researchers associate the high technological level of the processing industry with significant and systematic investments in R&D, but this approach limits the understanding of the factors that determine the technological level of industries, because in addition to significant expenditures on R&D, high-tech companies are characterized by the presence of modern high-performance equipment, technologies and intangible assets, availability of highly qualified personnel, development and implementation of new effective methods of management and organization of production, orientation of business to the global market, availability of financial resources.The proposed definition of the technological core (high-tech sector) is the processing industry, which is based on significant investments in research and development, the presence of significant amounts of intellectual property, intangible assets, modern equipment and technologies, the presence of highly qualified human capital, modern methods of management and production organization. This ensures the creation of high-tech goods with a high level of added value and a high level of labor productivity, which is higher than in other branches of the processing industry.The general formula of the technological core (high-tech sector) of the processing industry is proposed - these are industries that have a high level of availability of various types of capital and a high level of efficiency in their use.Two methodical approaches to the assessment of the technological level of processing industry branches are distinguished: resource-based and result-oriented. According to the first approach, the assessment of the technological level of branches of the processing industry is carried out on the basis of the availability of resources: knowledge-intensive (intangible assets), fixed assets, human capital (level of education and qualification of employees), organizational capital. According to the second approach, the assessment of the technological level of the branches of the processing industry is carried out on the basis of their effectiveness in terms of the performance of their functions (purposes, missions), which are determined by the interests of the population, business and the state, including the creation of high-tech products with a high level of added value and high labor productivity .As the main indicator for assessing the technological level of processing industries, it is proposed to use the gross added value, which in its essence is an integral indicator of the effectiveness of the industries and reflects the influence of such factors as scientific capacity, capital resources, the level of human and organizational capital, etc. The assessment of the technological level of industries based on these indicators is based on the hypothesis - the higher the technological level of the industry, the higher the labor productivity (gross added value per 1 employee).Conclusion. Based on the analysis of existing points of view on the essence of the concepts of "technological core", "high-tech industries", "high-tech sector" of industry, a definition of the concept of "high-tech industry" is proposed, as well as the formula of this concept in the context of capitalization. Determined methodical approaches to the assessment of the technological level of branches of the processing industry.