During the course of a transmission‐electron microscope characterization of nickel electrodeposits, it was found that deposits contain a high density of linear defects whose image contrast is not the same as is expected from dislocation lines. A detailed analysis of these defects using electron diffraction techniques showed that these images are similar to a line of dilatation. It has been suggested that these linear defects probably are generated at growth steps as a result of the incorporation of hydrogen during electrocrystallization.