Subject of study. The subject of the study is theoretical and methodical approaches to determining the level of effectiveness of country’s international specialization. The purpose of the study is to reveal the essence of economic complexity and product space concepts as the basis for the national economic systems development; to determine the effectiveness of the economic specialization of Ukraine; to formulate theoretical principles and practical recommendations for improving economic specialization and accelerating Ukraine’s economic growth. Research methods. The methodological principles the research relies on include a set of general and special methods of scientific knowledge, including comparative and statistical analysis, index method and time series analysis method. Results. This article looks into modern methodological toolkit to assess the role and place of a country in global labor distribution, as well as the country’s potential to ensure a high level of prosperity of its people. It analyzes the concept of product space that demonstrates the existing industrial capacity of a country. The paper exhibits the characteristics of different product groups through the prism of their economic complexity and ability to serve as a source of accelerated growth. It generalizes the characteristics of «low quality» economic activities as the subject of international specialization of a country. The article analyzes the existing economic specialization of Ukraine and its potential for improvement. The work emphasizes the reasonableness of a targeted use of «modernizing» type of economic policy to improve economic specialization and to accelerate economic development of the country and it also accentuates the threat of decrease in economic complexity and loss of economic growth potential in case of laissez–faire policy. Conclusions. The economic complexity and product space concepts are solid methodological basis for describing and explaining the historical laws of economic development. Earlier, the economic theory didn’t have proper methodology and tools to comprehensively explain radically different проeconomic trajectories in different countries of the world. The application of economic complexity and product space concepts shows the ineffectiveness of economic specialization of Ukraine, proves the possibility of successful structural transformations of the economy, warns against the losing potential of economic growth in the case of «non–interference policy», arguing the expediency of purposeful use of the «modernization» type of policy to accelerate the country’s economic growth.