The rapid development of information technology provides high growth rates of e-commerce. Today, e-business plays an important role in the structure of economies of advanced countries. In Ukraine, it develops more slowly than in neighbouring countries due to economic, social and political instability, low purchasing capacity of the population, lower demand for goods and services, devaluation of hryvnia, currency fluctuations, etc. However, domestic economists predict that the importance of e-commerce for the Ukrainian economy will increase annually. In such circumstances, the issue of identifying relationships between e-commerce and investment in research and development with the country's economic development becomes relevant as well as finding of tools for measuring the extent of e-commerce's impact on economic growth. The aim of the article is to construct a set of economic and mathematical models to assess the impact of e-commerce and investment in research and development on the country's economic development. Comparing the results of modelling in three countries, it has been determined that the value of e-commerce and R&D expenditures is more significant for GDP per capita growth in Ukraine and Poland due to the higher level of ICT development in Austria and its approximation to the saturation point relative to the growth rates of innovation industries. While comparing the levels of exposure to e-commerce and R&D costs in these countries, it was found that e-commerce occupies the first position only in Austria. While analysing the parameters of the models of three countries, it has been determined that GDP per capita is the most sensitive to changes in the indicators in the Ukrainian model. That demonstrates that the economy of Ukraine is less stable compared to Poland and Austria. Expenditure on R&D and e-commerce has a significant impact on the country's economic development and contributes to increasing of gross domestic product and productivity of manufacture.