We report here the observations and analysis of defects and domain structures in SBA-16 mesoporous films on molecular level using high resolution transmission electron microscopy. The films were made by dip-coating and have layered structure. Domain boundaries both perpendicular and parallel to the substrate were observed. It was found that while some observed low angle and high angle domain boundaries are similar to that found in normal crystals, distortions analogue to that existing in liquid crystal were also observed. The results are shown to provide useful information for understanding the growth mechanism and the properties of the film. (c) 2005 Elsevier B.V. All rights reserved.