The radioactivity of the superheavy nuclei ${}^{250−275}$Db is studied and presented using the Coulomb and proximity potentials. The half-lives corresponding to different decay modes such as α, cluster decay (${}^{12}$C, ${}^{14}$N,${}^{18,20}$O, ${}^{23}$F, ${}^{20}$Ne, ${}^{34}$S, ${}^{28}$Mg and ${}^{40}$Ca) and spontaneous fission in the superheavy nuclei ${}^{250−275}$Db are studied. The studied half-lives are compared with the available experiments. The decay modes and the branching ratios of isotopes of dubnium are presented. The isotopes of dubnium, ${}^{254−263}$Db, are identified as α emitters, whereas isotopes such as ${}^{250−253}$Db and ${}^{264−275}$Db are identified as having spontaneous fission. The identified alpha emitting isotopes of dubnium have decay energies from 6 MeV to 10 MeV and half-lives 1 ms to 100 s. The possible projectile–target combinations to synthesise the superheavy nuclei ${}^{253−263}$Db were predicted. The fusion of spherical projectile and target yields larger evaporation residue cross-sections.