A novel series of chalconyl homologue derivatives with RO.C6H4.COO.C6H4.CO.CH:CH-C6H4.N.(CH3)(2) (Para) have been synthesized and thermotropically studied with a view to understanding and establishing the effect of molecular structure on mesomorphic behavior of the novel homologues. The series consists of thirteen homologues (C-1 to C-18). C-7 to C-18 homologues are smectogenic, C-4 to C-18 nematogenic and C-1 to C-3 nonmesomorphic. Thus, novel chalconyl series is predominantly nematogenic and partly smectogenic. Transition temperatures and textures of mesophases were determined using an polarizing optical microscope (POM) equipped with a heating stage. Analytical and spectral data confirmed molecular structures of homologues. Phase transition curves showing phase behavior in a phase diagram behaved in normal manner. Thermal stability for smectic and nematic are relatively low at 59.6 degrees C and 76.6 degrees C respectively whose, smectogenic and nematogenic phase length vary from 12 to 16 degrees C and 06 to 20 degrees C, respectively. Mesomorphic behaviors of the present series are compared with a structurally similar known homologous series.