Twin dimers (TDs) with a different linking group (ester or ether) between the mesogenic group (cyanostilbene moiety) and the flexible spacer were synthesized to clarify the effect of the linking group on the mesomorphic properties. The sequence of the ester linking group and the position of the cyano group in the mesogenic core made an important contribution to the thermal properties of the twin dimers. A remarkable odd-even effect in the phase transition temperatures and entropy changes from a nematic phase to an isotropic fluid was observed for all the synthesized twin dimers.