We study the properties of dual Sobolev space $H^{-1, q}(\mathbb{X}) = \big(H^{1, p}(\mathbb{X})\big)'$ on a complete extended metric-topological measure $\mathbb{X} (X, \tau, \rm{d}, \rm{m})$ for $p\in (1, \infty)$. will show that crucial role is played by strong closure $H_{{\rm{pd}}}^{ - 1, q}\left({\mathbb{X}} \right)$ $L^q(X, in q}(\mathbb{X})$, which can be identified with predual $H^{1, ...