Femtosecond nanocrystallography provides a novel concept for structure determination, where X-ray diffraction “snapshots” are collected from a fully hydrated stream of nanocrystals, using femtosecond pulses from the world's first high energy X-ray free-electron laser, the Linac Coherent Light Source. Photosystem I was used as the model system for the first serial femtosecond crystallography experiments that showed the proof of concept that diffraction of nanocrystals can be observed using femtosecond pulses that are 1012 stronger than 3rd generation synchrotron sources and destroy any material that is placed in its focus ,. By using femtosecond pulses briefer than the time-scale of most damage processes, femtosecond nanocrystallography overcomes the problem of X-ray damage in crystallography . Data collected at the new CXI LCLS beamline at higher energy showed that the concept of fs crystallography extends to atomic resolution , and extends to membrane proteins crystallized in lipidic environments ,. Femtosecond crystallography also opens a new avenue for determination of protein dynamics. First experiments on the proof of principle for time resolved serial femtosecond nanocrystallography have been performed on Photosystem I-ferredoxin  and Photosystem II nano-crystals  and conformational changes of the Mn4Ca cluster and its protein environment were observed for the first time in the transition from the dark S1 to the double excited S3 state . These experiments pave the way the determination of molecular movies of the dynamics of membrane proteins "at work" in the future including the determination of a molecular movies of water splitting.