The interest toward Small Modular nuclear Reactors (SMRs) is growing, and the economic competitiveness of SMRs versus large reactors is a key topic. Leveraging a systematic literature review, this paper firstly provides an overview of “what we know” and “what we do not know” about the economics and finance of SMRs. Secondly, the paper develops a research agenda. Several documents discuss the economics of SMRs, highlighting how the size is not the only factor to consider in the comparison; remarkably, other factors (co-siting economies, modularisation, modularity, construction time, etc.) are relevant. The vast majority of the literature focuses on economic and financial performance indicators (e.g. Levelized Cost of Electricity, Net Present...