Tetrahydrofuran (THF) is an extremely valuable solvent that can also be polymerized into polytetramethylene ether glycol (PTMEG), which is the precursor for spandex fibers. Lycra®, a recognized top producer of spandex, has experienced a recent increase in Lycra® demand. Thus, the INVISTA Company has increased the production capabilities of their Gulf Coast Lycra® plant and has commissioned another THF production plant to be built on the same premises. The proposed plant will utilize a maleic acid byproduct from an internal upstream plant and will produce 100 million tons of THF per year. The THF must be at least 99.95% by mass THF, since lower purity THF contains more –OH groups that would terminate the polymerization reaction required to synthesize spandex fibers. This report provides a thorough design and economic analysis for the manufacture of THF in the Gulf Coast. Process flow sheets and a detailed description of all utility requirements and equipment are provided and analyzed. It is shown that the plant is extremely profitable for its expected 15 year lifespan, with an expected investor’s rate of return of 32.7%, return on investment of 45.9%, and net present value of $54.3 million (at a discount rate of 15%). With design commencing in 2009, construction in 2010, and operation beginning 2011, the breakeven year is expected to be 2015.