The compound ThPd2B2C has been studied with high-resolution electron microscopy and electron diffraction. ThPd2B2-xC adopts the LuNi2B2C structure with a layer sequence (ByNi2BzLuC)n in which the B composition and the exact position of the C are still uncertain. No intergrowths or planar defects are observed. The c-axis in the thinner parts of the crystals (<50nm) was observed to decrease up to about 0.5 nm when irradiated by the electron beam. © 1994.