In electrocatalytic conversion of earth-abundant small molecules (e.g., H2O, O2, CO2, N2), thorough understanding of the interface chemistry under the operating conditions is the cornerstone of design and construction of high-performance catalytic systems (electrolytes and electrodes). Frequently, limited comprehension of characterization tools leads to bewilderment in the system selection and/or experimental design. This perspective discusses the advance, limitation, and outlook of the state-of-the-art operando techniques involving investigation of electrocatalytic interfaces, including IR, Raman, UV-vis, XAFS, Mössbauer spectroscopy, AP-XPS, AFM, and SECCM. This perspective aims to help researchers in aspects of system selection, experimental design, and mechanism study in electrocatalysis.