A significant fraction of the product energy from oil shale retorting is contained in the retort off gas. Most oil shale processes use the retort off gas from plant fuel. The H/sub 2/S and NH/sub 3/ in retort off gas produce too much SO/sub 2/ and NOX to allow burning without a pollution control system. We used the ASPEN flowsheet simulator to model retort off-gas cleanup by venturi scrubbers. Venturi scrubbers are commonly used to remove particulates from gas streams, but the scrubbing liquid also absorbs some NH/sub 3/ and H/sub 2/S from the gas. The ASPEN venturi scrubber model makes good predictions of the particulate removal efficiency. The ASPEN estimates for H/sub 2/S and NH/sub 3/ absorption are higher than the equilibrium absorption predictions made by a state-of-the-art sour water vapor-liquid equilibrium model, TIDES. The discrepancy probably results from trying to simulate an electrolyte system with a vapor-liquid equilibrium model that is designed for molecular systems. The simulation indicates that a venturi scrubber may absorb enough NH/sub 3/ to serve as the primary NH/sub 3/ removal system. The H/sub 2/S absorption is quite low, however, and some other process is needed to remove the H/sub 2/S. 17 references, 6 figures, 3 tables.