The instrumentation and experimental setups needed to investigate catalysts by X-ray absorption spectroscopy (XAS) under in situ and operando conditions are briefly described. The relevance of the simultaneous collection of XAS data while monitoring the activity and selectivity of the catalyst (operando setups) is stressed and the compromises that are necessary to construct an operando cell are discussed. The same approach is used for cells that allow additional simultaneous data collection (X-ray powder diffraction, small-angle X-ray scattering, infrared, Raman or UV–visible). The role of time-resolved and space-resolved experiments is discussed, together with the need for sophisticated software that is able to handle a huge amount of XAS spectra coupled with other independent data collections.