We have applied the AUTOPLANT®, manufactured by Chemspeed Technologies, Inc, Monmouth Junction, N.J. to AFEX pretreatment of corn stover. The AUTOPLANT® is a workstation that is comprised of twelve (12) 100 mL stainless steel high pressure reactors with stirrers. It includes a robotic auto-pipetter, which can deliver precise amounts of aqueous fluids to the biomass in the reactors. Each reactor also has a precision pump to deliver exact amounts of ammonia.  We have shown that the AFEX pretreatment can be done under controlled conditions (including temperature, pressure, ammonia/water delivery and residence time) using the AUTOPLANT®.  Preliminary AFEX pretreatment, followed by enzyme hydrolysis, (72h) has shown that introducing an ammonia/water mixture, instead of 100% anhydrous ammonia to biomass, can increase the glucose yield after hydrolysis by over 15% compared to using 100% anhydrous ammonia.  Also, we have found that nitrogen over-pressure increases yield substantially by forcing the ammonia in the system into the liquid phase, where it can react with cell wall components rather than being lost into the headspace.  The ability of the AUTOPLANT® to provide superior control of AFEX conditions during pretreatment, allows us to investigate these two effects (aqueous ammonia and nitrogen overpressure) in addition to the effects of temperature, ammonia to biomass loading and residence time.