The -decay and spontaneous ¯ssion (SF) half-lives for even{even isotopes of superheavy nuclei in the range 106 Z 124 are predicted using nuclear double-folding and Coulomb potentials. The -decay half-lives are computed based on WKB approximation for tunneling probability through potential barrier. The half-lives of SF have also been calculated using a semi-empirical relation constructed by Santhosh et al. [Nucl. Phys. A 832, 220 (2009)]. Our calculated half-lives of cold SF and -decay are compared with the available experimental data. This comparison indicates that our obtained half-lives are in good agreement with the available experimental data. The competition between -decay and SF is also analyzed in detail and the decay modes are predicted for the unknown cases. Variation of -decay and SF half-lives with mass number of the parent isotopes for each nucleus revealed the major role played with shell e®ect.
