We study two-loop quantum corrections to the low-energy effective actions in N = (2, 2) and N = (4, 4) SQED on the Coulomb branch. In the latter model, the low-energy effective action is described by a generalized Kähler potential which depends on both chiral and twisted chiral superfields. We demonstrate that this generalized Kähler potential is one-loop exact and corresponds to the N = (4, 4) sigma-model with torsion presented by Roček, Schoutens and Sevrin [1]. In the N = (2, 2) SQED, the effective Kähler potential is not protected against higher-loop quantum corrections. The two-loop quantum corrections to this potential and the corresponding sigma-model metric are explicitly found.