Electron crystallography is a method to determine the arrangement of atoms in solids using a transmission electron microscope (TEM).

This method works in many cases where X-ray crystallography does not. The latter needs large 3-D crystals to work.

Protein structures are usually done from 2-dimensional crystals (sheets or helices), polyhedrons such as viral capsids, or dispersed proteins. Electrons can be used in these situations, whereas X-rays cannot, because electrons interact more strongly with atoms than X-rays do.

The clear differences between intensities of the diffraction spots can be used in crystal structure determination