One of the most commonly cited anticorrosion solutions in the geothermal industry is by pH modification by NaOH dosing which has been reported to be effective by various geothermal sites. Though not widely used in geothermal plants another way of retarding the effects of corrosion is by application of coatings. Due to the relatively high-temperature demand of geothermal process coatings to be applied must have good thermal stability resistance to abrasion (erosion) and resistance to chemical attack. High-velocity solids will impinge on the walls of the pipe eroding the metal. Erosion together with corrosion would have a synergistic effect on the rate of metal dissolution making it a critical factor to consider in operating under highly erosive and corrosive environment. High-temperature stable polymer nanocomposite coatings of polybenzoxazines (PBZ) modified with rubber (PBZ-R) with varying amounts of nanoclay (MMT) was made. The enhancement of the mechanical properties of PBZ-R by addition of MMT by its intercalation/exfoliation into the polymer matrix was supported by XRD thermogravimetric tests hardness test and adhesion tests. Results of electrochemical measurements showed that the nanocomposite coatings exhibited good anti-corrosion property. PBZ-R alone offered corrosion protection to the carbon steel in acidic geothermal brine. This is due to the low water absorption capability of PBZ which prevents the corrosive fluid to penetrate into the coating. Addition of the nanoclays further increased the corrosion protection of the nanocomposite coating with an optimum loading of 5 % MMT. The stability and the protection efficiency was also evaluated under high temperature and high-pressure brine tests conditions.