This paper reports the development of electrospun zein fibers with improved water stability and tensile strength for potential drug delivery. The low morphological stability in aqueous environment and poor mechanical properties in dry and wet states have restricted the applications of electrospun protein materials, though these materials possess a unique structure, special adsorption properties, biocompatibility and biodegradability. In this study, the electrospun zein fibers were modified by non-toxic citric acid cross-linking catalyzed by NaOH. An up to 183% enhancement in dry tensile strength and an up to 448% improvement in wet tensile strength were generated. The cross-linked fibers were able to maintain their fibrous structure for 15 days in phosphate-buffered saline at 37 degrees C. Moreover, those cross-linked electrospun zein fibers showed a potential in controlled drug delivery with a 58% drug-loading efficiency and a sustained profile drug release in artificial gastric juice. (C) Koninklijke Brill NV, Leiden, 2011