AbstractPhotodissociation action spectroscopy has made a great progress in expanding investigations of gas‐phase ion structures. This review deals with aspects of gas‐phase ion electronic excitations that result in wavelength‐dependent dissociation and light emission via fluorescence, chiefly covering the ultraviolet and visible regions of the spectrum. The principles are briefly outlined and a few examples of instrumentation are presented. The main thrust of the review is to collect and selectively present applications of UV‐vis action spectroscopy to studies of stable gas‐phase ion structures and combinations of spectroscopy with ion mobility, collision‐induced dissociation, and ion–ion reactions leading to the generation of reactive intermediates and electronic energy transfer.