In this study, modified fibrous mats of poly(ethylene oxide) (PEO) were fabricated through the versatile technique of electrospinning. Acrylic monomers were added to PEO with different composition ratios, and the mats were irradiated. The kinetics of photo-cross-linking reaction in the presence of the acrylic cross-linkers, as well as the structural, thermal and mechanical properties of the nanofibers, were studied. The morphology of the fibrous membranes before and after water treatment was monitored, and the insoluble fraction of the fibers was measured. As a result, by tuning the photo-cross-linking reaction, the control over fibers properties was feasible. The photo-cured PEO-based nanofibrous mats showed the solubility resistance needed to use them as membranes and to apply them in aqueous environments, as in water treatment processes and biomedical applications.