An electrically conducting composite based on bacterial cellulose (BC) and polypyrrole (PPy) was prepared through in situ oxidative polymerization of pyrrole (Py) in the presence of BC membrane using ammonium persulfate (APS), as an oxidant. The electrical conductivity, morphology, mechanical properties and thermal stability of the composites obtained using APS (BC/PPy·APS) were evaluated and compared with BC/PPy composites prepared using as oxidant agent Iron III chloride hexahydrate (FeCl3·6H2O). The morphology of the BC/PPy·APS composites is characterized by spherical conducting nanoparticles uniformly distributed on the BC nanofiber surface, while the composites produced with FeCl3·6H2O (BC/PPy·FeCl3) is composed of a continuous conducting polymer layer coating the BC-nanofibers. The electrical conductivity of BC/PPy·FeCl3 was 100-fold higher than that found for BC/PPy·APS composites. In order to understand the site-specific interaction between PPy and BC functional groups, both composites were characterized by Fourier transform infrared (attenuated total reflectance mode) spectroscopy attenuation reflectance (FTIR-ATR) and X-ray photoelectron spectrometry (XPS). The affinity between functional groups of PPy·FeCl3 and BC is higher than that found for BC/PPy·APS composite. In addition, the tensile properties were also influenced by the chemical affinity of both components in the polymer composites.