NOVELTY - A polymeric based anticorrosive coating composition comprises thermoplastic polymer (a) having molecular weight of 55000-200000, filler (b) and additive (c). The polymer (a) is prepared by polymerizing a resinous mixture containing (in weight%) styrenic based monomer(s) (10-60, preferably 30-45), acrylate based monomer(s) (5-45, preferably 15-35), methacrylate based monomer(s) (20-60, preferably 30-45), maleic anhydride (0.1-10, preferably 0.1-5) and solvent (20-70), initiator (0.1-3), and chain transfer agent (0.1-1). The chain transfer agent is n-dodecyl mercaptan.    USE - Polymeric based anticorrosive coating composition is used for coating metal (claimed). Uses include but are not limited to structural steel, machinery, industrial valve, motor, control panel, transformer, solar system, pipe line, storage tank and thermal power plant.    ADVANTAGE - The metal coated using the polymeric based anticorrosive coating composition has excellent chemical resistance, heat resistance, scratch resistance, flexibility, impact resistance, abrasion resistance, ultraviolet radiation resistance, flame retardance and moisture resistance.    DETAILED DESCRIPTION - A polymeric based anticorrosive coating composition comprises thermoplastic polymer (a) having molecular weight of 55000-200000, filler (b) and additive (c). The thermoplastic polymer (a) is prepared by polymerizing a resinous mixture containing (in weight%) styrenic based monomer(s) (10-60, preferably 30-45), acrylate based monomer(s) (5-45, preferably 15-35), methacrylate based monomer(s) (20-60, preferably 30-45), maleic anhydride (0.1-10, preferably 0.1-5) and solvent (20-70), initiator (0.1-3), and chain transfer agent (0.1-1). The styrenic based monomer is chosen from dimethylstyrene, trimethylstyrene, ( alpha )-methylstyrene, vinyltoluene, styrene, p-tert-butylstyrene and ( alpha )-methyl-p-methylstyrene. The acrylate based monomer is chosen from butylacrylate, t-butylacrylate, methylacrylate, hexylacrylate, ethyl-2-ethylacrylate, 2-ethoxyethylacrylate and 2-ethylhexylacrylate. The methacrylate based monomer is chosen from methylmethacrylate, 2-ethoxyethylmethacrylate, 2-butoxyethylmethacrylate, butylmethacrylate, t-butylmethacrylate, hexylmethacrylate and allylmethacrylate. The solvent is chosen from aliphatic and aromatic hydrocarbon. The initiator is chosen from di-t-butyl peroxide, 2,5-dimethyl-2,5-bis(tert-butyl-peroxy)hexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne-3, tert-butyl perbenzoate, dicumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, di-N-methyl-t-butyl percarbamate, lauroyl peroxide, acetyl peroxide, decanyl peroxide, t-butyl peracetate, t-butylperoxyisobutyrate, benzoyl peroxide and azobisisobutyronitrile. The chain transfer agent is n-dodecyl mercaptan. The filler is chosen from mica, barium sulfate, silica, calcium carbonate, talc and clay. The additive is chosen from reinforcing agent, coupling agent, pigment, colorant, dye, odorant, resin, tackifier, plasticizer, lubricant, stabilizer and antistatic agent. INDEPENDENT CLAIMS are included for the following:    (1) process for preparing polymeric based anticorrosive coating composition, which involves polymerizing resinous mixture containing styrenic based monomer, acrylate based monomer, methacrylate based monomer, maleic anhydride, solvent and initiator, adding n-dodecyl mercaptan to the resinous mixture during polymerization, when the degree of conversion of resinous mixture to the polymer is 75% or more, to obtain a thermoplastic polymer, cooling the thermoplastic polymer to temperature of 30-50 degrees C, and adding filler and additive to the thermoplastic polymer; and    (2) metal coated with the polymeric based anticorrosive coating composition.