The LB films of rare-earth (La, Nd, Sm, Eu, Tb) tristearates were prepared by means of spreading them directly on the solutions containing 5×10^-^5mol.dm^-^3 corresponding rare-earth trichlorides. The numbers of layers of various rare-earth tristearates could be formed up to 44 on a plate of hydrophobic glass at 25mN.m^-^1, with a transfer ratio of 0.7-0.8. X-ray photoelectron spectroscopy (XPS) verified the presence of La, Nd, Sm, Eu and Tb respectively in corresponding films. IR suggested that no hydrolysis took place in the process of deposition. X-ray diffraction of films in low angle region (0.3-14ⅲ) showed that the films are of periodic layered structure, the space of adjacent face of rare-earth ions is 4.7-4.8nm. According to the area-time curves in the deposition of rare-earth tristearates, there may be a change of film's type.

Key words: L-B MEMBRANE, STEARATE, RARE EARTH, STEARIC ACID FILM, SEDIMENTATION, X-RAY DIFFRACTION ANALYSIS, INFRARED SPECTROPHOTOMETRY