In case of low H-D/D ratio bubble columns, the sparger design dominates the performance of the bubble column reactor. However, scanty information is available in the published literature regarding the flow distribution in sparger. In view of this a comprehensive study was undertaken for a single pipe sparger and ring sparger covering a wide range of hole diameters (2-6 mm), pitch (2-8d(o)), pipe length (0.6 m and 1.5 m), ring diameter (0.38-0.57 m) and pipe diameter of rings (0.012-0.019 m). The flow variations have been related to geometric and operating parameters. Theoretical models available in the literature for pipe sparger have been critically analyzed. CFD simulations (ANSYS CFX-10) have been performed for all the pipe spargers and the results have been compared with the model of Acrivos et al. [A. Acrivos, B.D. Babcock, R.L. Pigford, Flow distributions in manifolds, Chem. Eng. Sci. 10 (1959) 112-124]. CFD simulations of all the ring spargers also have been performed, and the predictions show favorable agreement with experimental values of pressure and hole velocity. (C) 2007 Elsevier B.V. All rights reserved.