In this study we prepare a nanocomposite substrate from poly lactic acid (PLA) and graphene oxide (GO) using electrospinning. Determining the possible placement of graphene oxide nano-sheets in the electrospun fiber mats is the main goal of this work. The investigative methods employed include scanning electron microscopy (SEM), atomic force microscopy (AFM) micrographs, tensile modulus and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). It is shown that the localization of nanoparticle by different methods controls different final properties. We performed the study of the mechanical properties, surface chemical structure and topology of obtaining nanofiber mats. Studies showed that the location of GO sheets depends on the lateral size of them and based on this claim we estimated three possible locations for them: (1) small GO sheets (less than 200 nm) fully or partially inside the electrospun fibers, (2) some larger ones rolling around and on the fibers surface under the high applied voltage, and (3) parts of large sheets bridging between the fibers.