The film behaviors of a series of dendrons (G2, G3 and G4) on pure water subphase were investigated on a Langmuir-Blodgett trough. Moreover, the in situ observation of the film morphology and the film formation process was performed by using Brewster angle microscopy (BAM). The results indicate that the dendrons all can form solid monolayer on water surface, and the stability and reversibility of monolayer decrease as the generation of dendron increases. These phenomena may be mostly ascribed to the spatial interaction between molecules. (C) 2003 Elsevier Science B.V. All rights reserved.