A solid-phase growth of crystalline peptide nanowires at high temperatures influenced by aniline vapor under anhydrous conditions was reported. The formation of vertically well-aligned peptide nanowires on a solid surface were investigated through multiple tools, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, and thermal analytical tools like differential scanning calorimeters. The experiments were conducted under strictly anhydrous conditions in a vacuum desiccator to avoid the affect of water vapor in the final surface structure of the peptide thin film. It was found that the self-assembly of peptide nanowires from the film depended on both the aging temperature and the nature of the solvent vapor used. The peptide nanowires were thermally stable up to 200 °C without any loss in weight or structural integrity.