Two ferrocenyl-substituted N-acetyl-2-pyrazolines, N-acetyl-3-(2-furyl)-5-ferrocenyl-2-pyrazoline (Fc-1) and N-acetyl-3-(2-thienyl)-5-ferrocenyl-2-pyrazoline (Fc-2) electrospun fibers, were produced in the presence of plasma-modified chitosan (PMCh)/poly(ethylene terephthalate) (PET) supporting polymers with an electrospinning method. The morphological and chemical characterizations of the PMCh/PET/Fc-1 and PMCh/PET/Fc-2 electrospun fibers were determined by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis. Thermogravimetric analysis results indicated the presence of ferrocene within the PMCh/PET nanofibers. The electrochemical behavior of the PMCh/PET/Fc-1 and PMCh/PET/Fc-2 electrospun fibers were investigated by cyclic voltammetry measurements based on the ferrocene/ferrocenium redox couple. The new PMCh/PET/Fc-1 and PMCh/PET/Fc-2 electrospun fibers aggregated on the indium tin oxide were used for phosphate anion sensing. The highest oxidation peak currents were observed for the PMCh/PET/Fc-1 electrospun fibers at about 0.56V in 0.1M phosphate buffer. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43344.