CO 2 methanation is a well-known reaction that is of interest as a capture and storage (CCS) process and as a renewable energy storage system based on a power-to-gas conversion process by substitute or synthetic natural gas (SNG) production. Integrating water electrolysis and CO 2 methanation is a highly effective way to store energy produced by renewables sources. The conversion of electricity into methane takes place via two steps: hydrogen is produced by electrolysis and converted to methane by CO 2 methanation. The effectiveness and efficiency of power-to-gas plants strongly depend on the CO 2 methanation process. For this reason, research on CO 2 methanation has intensified over the last 10 years. The rise of active, selective, and stable catalysts is the core of the CO 2 methanation process. Novel, heterogeneous catalysts have been tested and tuned such that the CO 2 methanation process increases their productivity. The present work aims to give a critical overview of CO 2 methanation catalyst production and research carried out in the last 50 years. The fundamentals of reaction mechanism, catalyst deactivation, and catalyst promoters, as well as a discussion of current and future developments in CO 2 methanation, are also included.