The invention relates to compositions, methods and preparation of such compositions to protect metals from corrosion, especially acid corrosion. The compositions of this invention may be added to acids to protect metals from their corrosive influence, particularly at elevated temperatures. These compositions are of particular utility in the oil and gas (petroleum) industry. Also disclosed are “corrosion inhibition intensifiers” to enhance the corrosion inhibition properties of other corrosion inhibitors. Formulations which control ferric ions in acidic solutions are also disclosed. These may be combined with inhibited acids and some compositions provide both corrosion inhibition and ferric ion control.