A composite material containing polymeric nanofibers, themselves containing NO-donor molecules, imbibed with an elastomer matrix is permeable to both water and gas so that dissociation reactions in the presence of water releases NO gas in a sustained manner. The NO-donor nanofibers may be formed by synthesizing acceptable NO-donor molecules, blending such molecules in solution with PVP, PCL or PVAc, electrospinning the blend at relatively high voltage for form fiber mats, applying PDMS rubber to the fiber mat and crosslinking it. The resulting NO-releasing electrospun fiber composite may be used in medical devices such as catheters, stents, or vascular grafts, with the purpose of releasing nitric oxide within a controlled rate and for a sustained period of time, as well as other known medical applications for NO.