AbstractThe experimental scheme of flashspectroscopy can be employed to investigate extremely fast photophysical and photochemical processes of organic molecules. Essential changes in the method most be made, however, with regard to sample excitation and detection of absorption changes, if the processes to be investigated have characteristic times in the picosecond range.We have developed an instrument in which the sample is excited by pulses of a passively mode‐locked ruby laser followed by a ruby amplifier, while the probing light is provided by a xenon flash of a few microseconds duration. A new technique had to be developed for synchronizing the probing flash with the laser pulse train After passing through the sample cell the probing light is dispersed by a transmission grating and recorded by a streak camera having high time resolution. The method produces time‐resolved absorption spectra of the excited sample. We report details of the method and first results with an organic dye.