We report results of the studies relating to fabrication of an electrochemical biosensor platform based on in-situ electrosynthesized manganese oxide (Mn3O4)-polyaniline (PANI) nanofibers for detection of bisphenol A (BPA), an endocrine disrupting chemical. The spherical Mn3O4 nanoparticles synthesized using cetyltrimethylammoniumbromide were modified with PANI in presence of polyvinyl sulphonic acid and glutaraldehyde. The tyrosinase (Tyrs) molecules covalently immobilized on the PANI-modified Mn3O4 nanofibers surface were characterized using X-ray diffraction, electron microscopy and Fourier transform infrared spectroscopy. This electrochemical biosensor exhibits a response time of 20 s, sensitivity of 0.776 mA μM−1 L cm−2, respectively, and 0.134 mA μM−1 L cm−2 in the concentration ranges, 0.004–0.09 × 10−6 mol L−1 and 0.2–0.8 × 10−6 mol L−1 of BPA. © 2016 Elsevier B.V.