The chemical species evaporated from porous BC4N compound in a de are plasma were condensed as powders onto a metal disk cooled with water. The powders collected from the disk were characterized by high-resolution transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). The microstructures observed by TEM and the K-edge absorption data for B, C and N atoms analyzed by EELS indicated the presence of three types of nanotubes; they were a carbon, a boron nitride and a composite nanotube of carbon with boron nitride. However, a homogeneous phase of a BCxN nanotube could not be obtained. The reasons for this were discussed based on the differences in vapor pressure between carbon and boron nitride. Also, a possible formation mechanism of the nanotubes was briefly discussed.