A technique of carbon film synthesis based on an electrochemical process was developed. A solution of acetylene in liquid ammonia was employed as the electrolyte. Films were deposited at the metallic anode. Two types of films were produced. Films of type I are transparent and fragile, whereas those of type II are black and plastic. The films were investigated by the electron diffraction method and Raman spectroscopy. The electron diffraction data for type I films demonstrate the films’ high degree of crystallinity. Values of lattice plane spacings agree with data on cubic diamond modifications. The Raman spectrum of type I films shows a line at 1334cm−1(full width at half-maximum equal to 15cm−1),inherent in that of diamond and an essentially amorphous carbon component. Spectra of the type II films do not feature the Raman peak of diamond. ©1997 American Institute of Physics.