The aim of the study is to obtain new knowledge about mechanisms contributing to the development of product eco-innovations by companies-suppliers of environmentally sound technologies in countries classified as moderate innovators. The research uses qualitative methods and it is based on multiple case-study analysis. The research results reveal that eco-innovations are developed thanks to feedback loops between companies’ knowledge, technical expertise and market information (obtained from customers and competitors). The importance of these elements of the mechanism contributing to the development of eco-innovations differ, however, between types of enterprises in the countries studied (i.e. companies-suppliers of finished products and the companies supplying the products components). Component product providers place greater emphasis on tracking their competitors' moves and analysing their products, while final product suppliers focus more on customer needs and their actions to great extent depend on the exclusive expertise and experience of their executives.