We study analytic aspects of U(n) gauge theory over a toric noncommutative manifold M θ . We analyse moduli spaces of solutions to the selfdual Yang-Mills equations on U(2) vector bundles over four-manifolds M θ , showing that each such moduli space is either empty or a smooth Hausdorff manifold whose dimension we explicitly compute. In the special case of the four-sphere S 4 θ we find that the moduli space of U (2) instantons with fixed second Chern number k is a smooth manifold of dimension 8k − 3. e-print archive: