Activated carbon is an important gas and liquid filtering media thanks to its porous structure. Activated carbon is produced in a number of forms namely, powder, granule and recently fibers or fiber assemblies. The size of particles in powders plays an important role in determining its behavior. In this context, decreasing the size of particles to nano dimensions brings about drastic changes in the performance of powders as a result of increased specific surface area. Nanoparticles can be produced through vapor, liquid or solid processes. Electrospraying is an important technique which is capable of natural or synthetic polymeric nanoparticles. In recent years, activated carbon fibers and especially activated carbon nanofibers have attracted the attention of many researchers worldwide in air and water pollution control as well as other applications like filters and masks with an increasing importance trend. This research aimed at producing activated carbon nanoparticles and carrying out an investigation on their porous structure as well as comparing them with activated carbon nanofibers of similar diameter. The precursor for the activated carbon nanoparticles were three polyacrylonitrile electrosprayed nanofibers with an average diameter of 82.3 nm, 96.7 nm and 117.7 nm. The results showed that activation process leads to a decrease of about 13% for the size of polyacrylonitrile nanoparticles. The activated carbon nanparticles had an average size of 71.7 nm, 85 nm and 100.8 nm. The results also showed that the iodine number for the three activated carbon nanoparticle samples was about 1200 mg/g, while the iodine number of the activated carbon nanofibers was 985 mg/g indicating a higher absorption capacity for activated carbon nanoparticles when compared with activated carbon nanofibers. The specific surface of activated carbon nanoparticles measured by BET analysis was 1604, 1620 and 1641 m 2 /g, where as for activated carbon nanofibers was only 583 m 2 /g. The total pore volume of activated carbon nanoparticles was 4 times higher than that of activated carbon nanofibers. Activated carbon nanoparticles showed also a micropore volume three times higher than that of activated carbon nanofibers. The distribution of nanoparticle size in each sample was found to be wider than that of activated carbon nanofibers. Basically this research reveals the superiority of the absorption properties of activated carbon nanoparticles to activated carbon nanofibers. Keywords : Electrospray, PAN nanoparticle, Activated carbon nanoparticle, Specific surface area, BET, Iodine number.