A uniform fluidization exists between minimum fluidization velocity and minimum bubbling velocity. Experimental investigations have been carried out for determination of minimum bubbling velocity and fluidization index for non-spherical particles in cylindrical and non-cylindrical beds. In the present paper equations have been developed for the prediction of minimum bubbling velocity for gas-solid fluidization in cylindrical and non-cylindrical (viz. semi-cylindrical, hexagonal and square) beds for non-spherical particles fluidized by air at ambient conditions. A fairly good agreement has been obtained between calculated and experimental values. Based on the experimental data it is concluded that under similar operating conditions minimum bubbling velocity and the fluidization index are maximum in case of either semi-cylindrical conduit or hexagonal conduit for most of the operating conditions and minimum in case of square one. It is further observed that the range of uniform (particulate) fluidization is maximum in case of semi-cylindrical bed for identical operating conditions. (c) 2005 Elsevier B.V. All rights reserved.