The development of a water-based polymer system that could be photocrosslinked during the drilling of fragile formations could be of a great interest. In this context, aqueous solutions of poly(ethylene oxide) (PEO) were photocrosslinked by ultraviolet radiation in the presence of benzophenone (BP). The photochemical crosslinking reaction showed a rate constant of 1 x 10(12) L mol(-1) s(-1), indicating the formation of a complex between the reactants. The crosslinked PEO was fully characterized showing an yield dependency on the irradiation time, concentration of benzophenone, and on the presence of oxygen. During the study of the effect of BP concentration, it was observed that low concentrations and the presence of oxygen favor chain scission, while crosslinking was the dominant effect at higher BP concentrations. The storage modulus (G) value for some of the materials was found to be higher than the loss module (G) suggesting a predominantly elastic solid-like behavior which was corroborated by the scanning electron microscopy (SEM) results. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2458-2467, 2013