Carbon films were deposited on silicon, quartz, and potassium bromide substrates from an ion beam. Growth rates were approximately 0.3 μm/hour. The films were featureless and amorphous and contained only carbon and hydrogen in significant amounts. The density and carbon/hydrogen ratio indicate the film is a hydrogen deficient polymer. One possible structure, consistent with the data, is a random network of methylene linkages and tetrahedrally coordinated carbon atoms.