DFT calculations are applied to devise some stable C20 nSin heterofullerenes with n <= 8. Si atoms are doped at eight selected symmetric positions in such a way that all of them are completely isolated from each other. In contrast to previous reports, none of the computed heterofullerenes collapses to open cage structures. High charge transfer on the surfaces of our stable heterofullerenes provokes further investigations on their possible application for hydrogen storage. (C) 2010 Elsevier B.V. All rights reserved.