Specifically deuterated liquid crystals, 4-n-pentylphenyl-4’-n-aikoxythiobenzoates (($) over bar nS5) with n = 7(($) over bar 7S5-d(26)) and n = 8(($) over bar 8S5-d(28)) were synthesized by esterification of the chain perdeuterated 4-n-heptyloxy and 4-n-octyloxybenzoyl chlorides with the chain perdeuterated 4-n-pentylbenzene-thiol. The mesomorphic properties of the deuterated ($) over bar 7S5-d(26) and ($) over bar 8S5-d(28) were determined by DSC. Phase transition temperatures as well as their enthalpy and entropy Values were almost always lower than the respective values for the non-deuterated analogues.