A prototype sulfuric acid mist monitor has been constructed for the purpose of detecting sulfuric acid-sulfur trioxide. The monitor utilized the selective condensation method with subsequent determination of sulfuric acid by measuring the conductivity of an aqueous isopropanol solution. The instrument is fully automated with a mass flow controller and standard TTL logic to allow for easy modification of the timinng circuit. After collection of the H2SO4-SO3 in the temperature controlled spiral condenser, the sample is washed into a conductivity cell for measurement. During conductivity measurement the condensor is rinsed with methanol and air dried prior to the next sample collection. The instrument was designed to measure from 1 to 100 mg/cu m H2SO4 and present the measurement within a 10 mv range. The sample timing cycle can be varied from 105 seconds to 999 seconds.