A new polymer made from the combination of three different monomers is known as terpolymer, which has high molecular weight. Terpolymerization is the joint polymerization of three or more monomer species. It is carried out to vary the properties of polymer such as hardness, strength, rigidity, heat resistance etc., It is used in high performance elastomers with excellent high temperature, oil and chemical resistance available as conventional copolymers and terpolymers. Special terpolymer can be designed for improving mechanical properties in moulding and extrusion applications. High viscosity terpolymer that provides excellent balance of physical properties for moulded products. Very high viscosity terpolymer for superior mechanical and composition set resistance provides improved adhesion to substrate. Terpolymer resin is used in ion exchange process to recover certain metal ions from waste solutions and for the purpose of waste water solution and removal of iron from boiler water. It is used in energy storage capacitors as high dielectric constant terpolymer. The terpolymeric ligand and its polychelates are used against certain pathogenic bacterias. Generally the terpolymer is synthesized by solution condensation, melt condensation or emulsion polymerization in an acid medium, base medium or catalyst. The recent trends in preparation and characterization of terpolymer and its chelates are discussed