Nanofibers of alpha-Fe2O3 and gamma-Fe2O3 have been obtained after the controlled calcination of precursor nanofibers synthesized by electrospinning. alpha-Fe2O3 nanofibers showed an irregular toruloid structure due to the decomposition of poly (4-vinyl) pyridine in air while gamma-Fe2O3 nanoparticles decorated nanofibers were observed after the calcination under N-2 atmosphere. Electrochemical measurements showed that different electrochemical behaviors were observed on the glassy carbon electrodes modified by alpha-Fe2O3 and gamma-Fe2O3 nanofibers. The electrode modified by gamma-Fe2O3 nanofibers exhibited high electrocatalytic activities toward oxidation of dopamine, uric acid and ascorbic acid while alpha-Fe2O3 nanofibers cannot. Furthermore, the gamma-Fe2O3 modified electrode can realize the selective detection of biomolecules in ternary electrolyte solutions. The synthesis of nanofibers of alpha-Fe2O3 and gamma-Fe2O3 and their electrochemical sensing properties relationship have been discussed and analyzed based on the experimental results. (C) 2018 Elsevier B.V. All rights reserved.