A three-dimensional gasdynamic model with constant burning rate is applied for the prediction of the maximum pressure rise from gaseous combustion in vented enclosures. A series of calculations for an enclosure with aspect ratio close to unity are presented. Both cases with and without obstacles in the enclosure are considered. Results of calculations are compared with a simple OD solution for spherical vessels. It is shown that, in cases without obstacles, the OD solution for the maximum reduced overpressures is close to the predictions of the detailed modeling. In cases with obstacles, the detailed simulation gives significantly higher overpressures than those from the OD model. However, in all the cases the reduced pressures are correlated well with the maximum flame surface area. (C) 2007 Elsevier Ltd. All rights reserved.