A novel azo ester homologous series of liquid crystals (LCs) 2(4'-n-alkoxy benzoyloxy) napthyl 1 azo-3 '' nitrobenzenes consists of eleven members of a series with enantiotropic nematogenic mesophase formation and without exhibition of smectogenic property by all the eleven homologs. The nematogenic mesophase textures are threaded or Schlieren. Solid-nematic and nematic-isotropic transition curves of the phase diagram behave in normal manner except for the decyloxy, dodecyloxy, and tetradecyloxy homologs. Analytical and spectral data confirm the molecular structures of homologues. Thermal stability for the nematic phase is 132.6 degrees C, and the degree of mesomorphism varies between 34 degrees C and 79 degrees C and the series if of a middle-ordered melting type. An odd-even effect is observed for the N-I transition curve with alternation of transition temperatures. The LC behavior of the series is compared with other structurally similar known homologous series to establish the relation between mesomorphism and molecular structure.