We study finite-temperature N = 1 SU (2) super Yang-Mills theory, compactified on a spatial circle of size L with supersymmetric boundary conditions. In the semiclassical small-L regime, a deconfinement transition occurs at T c 1/L. The transition is due to a competition between non-perturbative topological "molecules"-magnetic and neutral bioninstantons-and electrically charged W -bosons and superpartners. Compared to deconfinement in non-supersymmetric QCD(adj) [1], the novelty is the relevance of the light modulus scalar field. It mediates interactions between neutral bions (and W -bosons), serves as an order parameter for the Z (L) 2 center symmetry associated with the non-thermal circle, and explicitly breaks the electric-magnetic (Kramers-Wannier) duality enjoyed by non-supersymmetric QCD(adj) near T c . We show that deconfinement can be studied using an effective twodimensional gas of electric and magnetic charges with (dual) Coulomb and Aharonov-Bohm interactions, or, equivalently, via an XY-spin model with a symmetry-breaking perturbation, where each system couples to the scalar field. To study the realization of the discrete Rsymmetry and the Z remaining unbroken at the transition. Thus, the SYM transition appears similar to the one in SU (2) QCD(adj) [1] and is also likely to be characterized by continuously varying critical exponents.