[en] Highlights: • In summary, CP is found to self-assemble into distinct morphological structures under different environmental conditions: this macro cyclic conjugated molecule self organized into nanospheres and nanofibers accompanying natural evaporation of its butanol and toluene solutions on mica, silica and HOPG, respectively. • Intermolecular π-π bonding and electronic attraction is believed to be involved in the self-association processes, and affinity or likeness of the solvent molecules and the molecule-surface interactions may be responsible for the molecules to vary their assembly structures in response to the changes in their solvent and substrate. • The constructions of nanosized fibers may found applications in the field of supramolecular electronics. Cyclo [8] pyrrole (CP) is a porphyrin analogue containing eight α-conjugated pyrrole units which are arranged in a nearly coplanar conformation. The π-π interactions between CP molecules lead to regular aggregations through a solution casting process. Using tapping mode atomic force microscope (AFM), we investigated the morphology of self-assembled aggregates formed by deposition of different CP solutions on different substrates. We found that in the n-butanol solution, nanofibrous structures could be formed on the silicon or mica surface. Interestingly, on the highly oriented pyrolytic graphite (HOPG) surface, or silicon and mica surface with a toluene solution, only irregular spherical structures were identified. The difference in the nanomorphology may be attributed to distinct interactions between molecule-molecule, molecule-solvent and molecule-substrate.