Phase diagrams were constructed for the various binary systems made from compounds of structurally different mesogens; one component is from the five homologous series 4-(4'-substituted phenylazo)phenyl-4"-alkoxybenzoates (Ia-e) and the other from the similarly substituted homologous series 4-(4'-substituted phenyl carbonyloxy)phenyl-4"-alkoxy benzoates (IIa-e). Transition temperatures of all mixtures prepared were measured by differential scanning calorimetry and identified by polarized light microscopy. Polarity and polarizability of the investigated compounds could be varied by changing the substituent X (CH3O, CH3, Cl, CN and NO2), which covers a wide range of polarity, and the alkoxy-chain length, which varied between 6, 8, 14, or 16 carbons. (C) 2005 Published by Elsevier B.V.