We should not underestimate the role of in situ and operando spectroscopic techniques in increasing our level of understanding of chemical reactions. The electrochemical reduction of CO2 is not an exception. The application of analytical techniques such as infrared spectroscopy, Raman spectroscopy, X-ray absorption spectroscopy and UV-vis spectroscopy over the years has been crucial for investigating the oxidation state changes of the electrode materials, identifying active surface species, understanding reaction mechanisms and deriving selectivity trends. Hence, such tools are indispensable for the rational design of electrocatalytic materials. This chapter presents an overview of the main spectroscopic techniques that can be applied to the investigation of homogeneous and heterogeneous electrochemical reduction of CO2, notable cell designs for spectroelectrochemical experiments, as well as highlighting representative reports on the use of various techniques.