The local and average convective mass transfer coefficients from the porous medium surface of a horizontal rotating large-diameter cylinder were measured at a constant mass transfer state. Characteristics of local and average Sherwood numbers varying with rotational Reynolds numbers were investigated. Further, the critical Reynolds number (Re-r,Re-cri) was determined and analyzed. Based on the experimental results, equations correlating the average Sherwood number (Sh) and critical Reynolds number (Re-r,Re-cri) with the rotational Reynolds number (Re-r), Schmidt number (Sc) and Grashof number (Gr) have been obtained, respectively. (c) 2011 Elsevier Ltd. All rights reserved.