Oligosilanes with phenyl end groups, Ph(SiMe2)(n) Ph where n = 10, 11, 12 and 13, were synthesized and their thermal and structural properties were studied. Dodecamer and tridecamer possessed mesophases showing the interdigitated structure in the range of 126-139 and 127-155 degrees C, respectively. In the mesophase, the silicon chains adopted the all-trans conformation.