The report of the Baruch Committee on the rubber situation included a recommendation for a production of 60,000 ton per year production of Thiokol by the end of 1943. Thiokol is a type of synthetic rubber formed by the reaction between organic dihalides and inorganic polysulfides. They find wide application where resistance to petroleum oils, organic solvents, and low permeability. The purpose of this investigation was to design a Thiokol with a production of 2000 tons per year. Research was conducted to determine operating conditions for the production of sodium polysulfide, one of the raw materials for the production of Thiokol, and conditions for the Thiokol production. The information for the design of the ethylene dichloride, the other raw material of Thiokol, was obtained from literature. The studies of the polysulfide solution showed that 13.83 grams of sulfur would react with every 10. 2 grams of caustic when sulfur was in excess. The amount of sulfur that reacted was independent of the amount of excess sulfur. Other studies indicated that a dilution of 100 cc. of water per 10.2 grams of caustic was desirable, and that a period of 12 minutes of boiling gave the highest polysulfide content. Further time of boiling was not deleterious, but neither did the amount of sulfur as polysulfide increase. A complete sulfur analysis of the polysulfide solution showed a polysulfide content approximately 3.2 times that of the monosulfide indicating higher polysulfides than tetrasulfide being formed. Experiments conducted with the polysulfide solution as prepared and using just ethylene dichloride gave unsatisfactory results, although products obtained using lower temperatures were slightly better than those with higher temperatures. Magnesium chloride was unsatisfactory as a dispersing agent using the polysulfide as prepared, but ethyl alcohol gave satisfactory results. Studies of dilution yielded products of high values ranging from 91 to 75. Large amounts of freshly precipitated were satisfactory as dispersing agents but with small amounts the value of the product was 60. The highest valued product obtained was with 5 cc. of ethyl alcohol and dilution, but a satisfactory product, value 85, was obtained with one gram of magnesium chloride and dilution. Since the latter was more economical, these conditions were selected for the design of the Thiokol plant. Preconstruction cost accounting of the designed plant indicate an annual cost of $610,087 per year and a surplus of $589, 912 per year. This is based on a selling price of $0.30 per pound for Thiokol. / M.S.