This paper reviews the literature on environmental innovation (EI) and systematizes it by means of an original methodology identifying the main directions in which the literature on EI has developed over time. In order to do so, two algorithms are adopted and used to analyse a citation network of journal articles and books. The main path analysis reveals that this literature revolves around the following topics: i) determinants of EI; ii) economic effects of EI; iii) environmental effects of EI and iv) policy inducement of EI. Each of these topics is discussed and implications from the main findings as well as possible future research extensions are outlined.