Sodium Bichromate and Sodium Dichromate are one and the same since bi is derived from latin and di from greek. In the eighties and nineties Sodium bichromate was popular in Canadain Surface Finishing industry. Today Sodium Dichromate seems more popular. Regardless, Sodium Bichromate is an inorganic compound and a powerful oxidizing agent, which is highly corrosive. During the eighties and nineties Sodium Bichromate anhydrous was very popular in the manufacture of hexavalent chromates used in the general metal finishing. The sodium salt was very popular since it was around twenty times more soluble in water than potassium salt at 49 g/L at 0°C. Sodium Bichromate anhydrous and Sodium Bichromate dihydrate were both available, however Sodium Bichromate anhydrous was mostly used since it is more concentrated with about 7% more active ingredient than Sodium Bichromate dihydrate. Why buy water? However, today Sodium Dichromate dihydrate seems more readily available with a higher cost. Why? We have available Sodium Dichromate anhydrous.