We compute the extension of the lagrangian of N = 1 supersymmetric theories to the case in which some axion symmetries are gauged. It turns out that generalized Chern-Simons terms appear that were not considered in previous superspace formulations of general N = 1 theories. Such gaugings appear in supergravities arising from flux compactifications of superstrings, as well as from Scherk-Schwarz generalized dimensional reduction in M-theory. We also present the dual superspace formulation where axion chiral multiplets are dualized into linear multiplets.