A large number of laterally fluorinated 4-n-alkyl- and -alkoxy-phenyl 4'-n-alkyl- and -alkoxy-benzoates and 4-n-alkylphenyltrans-4'-n-alkyl- and -alkoxy-cyclohexane-1-carboxylates were synthesised. In these compounds, the lateral fluoro-substituent was situated in either the phenol or the carboxylic acid moiety of the molecules for the benzoate esters, but only in the phenol moeity for thetrans-cyclohexane-1-carboxylate esters. The nematic thermal stabilities for the fluorophenyl benzoate andtrans-cyclohexane-1-carboxylate esters and the fiuorobenzoate esters were compared with those for the corresponding non-fluorinated analogues. A nematic thermal efficiency order was derived for the 4-n-alkyl-fluorophenyl 4-n-alkylbenzoate andtrans4-n-alkylcyclohexane-1-carboxylate esters, but only in the case of the latter esters, which were extensively examined, was the smectic tendency of the system investigated.