Novel fibrous biocomposites comprising ulvan, a sulfated polysaccharide extracted from the green seaweed Ulva rigida, and either polycaprolactone or polyethylene oxide were successfully prepared using the electrospinning technique. The morphology and the chemical composition of the nanofibers were characterized using SEM and FT-IR analyses. Ulvan was found to incorporate well with the co-electrospun biocompatible polymers, conferring on the collective properties of these materials. Such nanofibrous matrices represent potentially useful materials in the biomedical sector as tissue engineering scaffolds, wound dressings, or drug delivery systems. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42153.