Abstract Resorcinol–formaldehyde activated carbon xerogels were synthesized at certain conditions, and their morphology was studied experimentally to examine their detailed nature on the nanoscale level, which has not been reported before. Traditionally, such materials are reported to consist of microspherical particles of carbon. A more detailed morphology was discovered in this study. Resorcinol–formaldehyde activated carbon xerogel microspheres were found to consist of nanoparticles with different and unique characteristic sizes depending on the used synthesis recipes. The characteristics of these nanoparticles were linked to their corresponding pore structures and elemental compositions. This new discovery adds new dimensions to their potential applications and material development.