PURPOSE: To obtain a liq. crystal polyesteretherimide which has favorable properties including high heat stability and solvent resistance by producing it from a bisimidodicarboxylic acid or its functional deriv.

CONSTITUTION: From a bisimidodicarboxylic acid represented by formula I [wherein Y is O, S, SO2, CO, or a group represented by formula II; Z is OH, OR3, OM (wherein M is a group equivalent to an ammonium cation) or NR3R4; R1 and R2 are each H, CH3, or C2H5; and R3 and R4 are each an org. group] or its functional deriv. is produced a liq. crystal polyesteretherimide represented by formula III (wherein A is a group represented by formula IV, V, or VI; and Y is the same as described above). Here, a suitable bisimidodicarboxylic acid is N-bis(4-carboxyphenyl)imide of 2,2-bis[4-(dicarboxyphenoxy) phenyl]propane. The polyesteretherimide of the invention is solid, crystalline, anisotropic even at a temp. higher than 375°C when melted, and highly birefringent.