Improved stabilizer compositions are provided which impart significant long-term stabilization to halogen containing polymers such as polyvinyl chloride. The improved stabilizer compositions incorporate an alkali-metal hydrogen phosphate compound, such as anhydrous disodium hydrogen phosphate, of a predetermined surface area. The novel inorganic phosphate enables a reduction in the amount of organmetallic stabilizer, if desired, while still yielding long-term stability in the resultant polymer, or the ability to raise process temperature and reduce cycle times of molding operations.