The nanofiber ability of an ulvan-rich extract, originated from the low cost biomass of the alga Ulva rigida, has been achieved for the first time via electrospinning. Ulvan-based uniform nanofibers were produced by being blended with poly(vinyl alcohol) (PVA). The nanofibers have an average diameter controllable down to 84 nm and present a highly ordered crystalline structure under transmission electron microscopy (TEM). A new complex fiber is created, which results from ulvan-rich extract and PVA ionic assembly and involves borate esters and divalent cations. The spinnability of this anionic sulfated polysaccharide-rich extract in combination with its interesting biological and physicochemical properties can lead to new biomedical applications such as drug release systems. (C) 2011 Elsevier Ltd. All rights reserved.