The electrospinning of sodium alginate, a natural biopolymer, was performed from aqueous solutions by blending with PEO, a biodegradable polymer. The conductivity and surface tension of solutions of sodium alginate and PEO were investigated by standard methods. The morphology, thermal, and mechanical properties of the electrospun nanofibers were studied using field emission scanning electron microscopy (FE-SEM), fourier transform infrared spectroscopy (FT-IR) energy dispersive X-ray (EDX), differential scanning calorimetry (DSC) and tensile testing. Uniform, smooth, and ultra-fine nanofibers with diameters of similar to 140-190 nm were obtained with solution concentrations of 6-7.2% and sodium alginate/PEO volume ratios of 30:70-50:50. The mechanical strength of the electrospun sodium alginate/PEO mats with good morphology was 21 MPa compared to PEO mats which had a strength of only 10 MPa. POLYM. ENG. SCI., 49:52-59, 2009. (C) 2008 Society of Plastics Engineers