Chemical environment-dependent supramolecular assembly of 11-helical α,β2,3-hybrid peptide which give hexagonal or rod-like microcrystalline structures is demonstrated. Apart from the modulatory role by P123, sequential use of organic co-solvents during the initiation and propagation phases is shown to contribute to the size and shape regulation during molecular organization. Comparison of powder XRD data and thermal analysis results suggested that the molecular arrangement in these aggregates is similar to that in their crystals. © 2012 The Royal Society of Chemistry.