Cold cathode field electron emission from thin films of a new organic compound Ca–Cu–B (B=betain) is observed. The microstructure of the film grown on an Al substrate by thermal evaporating technique is examined by scanning electron microscope and electron probe microanalysis, and it is found that a large number of carbon microparticles are embedded in the film. A transparent anode is used to image the spatial distribution of the emission sites and to measure the I–V characteristics, stability and turn-on field of the films. It is proposed that the presence of embedded carbon inclusions are responsible for the emission.