Abstract: The high molecular weight poly (ethylene oxide) was used to synthesize telechelic bromine terminated poly (ethylene oxide) polymers. The low molecular weight polystyrene anion was generated by living anionic polymerization by controlling monomer/initiator ratio. The living polystyrene anion was reacted with telechelic bromine terminated poly (ethylene oxide) polymers to obtain water soluble polystyrene-b-poly(ethylene oxide)-b-polystyrene tri-block copolymers. The effect of polystyrene-b-poly(ethylene oxide)-b-polystyrene (PS-b-PEO-b-PS) block copolymer on the mild steel corrosion in 1M sulfuric acid solution has been investigated at various inhibitor concentrations and temperatures by Potentiodynamic Polarization Study. The investigated results showed that the corrosion rate decreased significantly with increase in the concentration of inhibitors. The shape of polarization profiles of the polymer at various concentrations indicated their mixed-type nature of inhibition.