Electrospun fibers of 7-methyl-4-phenyl-8-(4'-methoxy)phenylazopyrazolo[5,1-c][1,2,4]triazine-3-carboxylic acid ethyl ester (PCA-4) and 7-methyl-4-phenyl-8-(2'-methoxy)phenylazopyrazolo[5,1-c][1,2,4]triazine-3-carboxylic acid ethyl ester (PCA-2) were produced using electrospinning technique. Poly(methylmethacrylate) (PMMA) was used as support electrospun polymer. The morphological and chemical characterizations of the PCA-4/PMMA and PCA-2/PMMA electrospun fibers were carried out by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis (SEM-EDX). The electrochemical behavior of the PCA-4/PMMA and PCA-2/PMMA fibers onto ITO electrodes was examined by cyclic voltammetry (CV) measurements. The new PCA-4/PMMA and PCA-2/PMMA fibers were used for phosphate anion sensing. PCA-4/PMMA fiber indicated the best current response to 0.2 M phosphate buffer solution at -0.67 V.