This paper presents a model and simulation results for the mitigation of a hydrogen-air deflagration by venting through a duct. A large eddy simulation (LES) model, applied previously to study both closed-vessei, and open atmosphere hydrogen-air deflagrations, was developed further to model a hydrogen-air explosion vented through a duct. Sub-grid scale (SGS) flame wrinkling factors were introduced to model major phenomena which contribute to the increase of flame surface area in vented deflagrations. Simulations were conducted to validate the model against 20% hydrogen-air mixture deflagrations (vent diameters 25 and 45 cm) and 10% hydrogen-air mixture deflagration (vent diameter 25cm). There was reasonable correlation between the simulations and the experimental data. The comparative importance of different physical phenomena contributing to the flame wrinkling is discussed. (C) 2007 Elsevier Ltd. All rights reserved.