Ba(1-x)LaxFe12O19 (0.00 <= x <= 0.10) nanofibers were fabricated via the electrospinning technique followed by heat treatment at different temperatures for 2 h. Various characterization methods including scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and microwave vector network analyzer were employed to investigate the morphologies, crystalline phases, magnetic properties, and complex electromagnetic parameters of nanofibers. The SEM images indicate that samples with various values of x are of a continuous fiber-like morphology with an average diameter of 110 +/- 20 nm. The XRD patterns show that the main phase is M-type barium hexaferrite without other impurity phases when calcined at 1100 degrees C. The VSM results show that coercive force (He) decreases first and then increases, while saturation magnetization (M-s) reveals an increase at first and then decreases with La3+ ions content increase. Both the magnetic and dielectric losses are significantly enhanced by partial substitution of La3+ for Ba2+ in the M-type barium hexaferrites. The microwave absorption performance of Ba0.95La0.05Fe12O19 nanofibers gets significant improvement: The bandwidth below -10 dB expands from 0 GHz to 12.6 GHz, and the peak value of reflection loss decreases from -9.65 dB to -23.02 dB with the layer thickness of 2.0 mm. (C) 2011 Elsevier B.V. All rights reserved.