The presence of halogens in high temperature corrosive environments presents special difficulties due to the volatility of most halide corrosion products. High temperature corrosion in such environments may occur by volatilization or by formation of porous, non-protective oxides. Penetration of oxide scales can also lead to internal attack by carbon, nitrogen or other environmental species, which might be benign in an uncontaminated atmosphere. As a result, materials that would develop protective oxide films and be corrosion resistant in most environments may be subject to accelerated attack when halogens are present. Several examples of attack in halogen containing environments will be described.