Poly (ortho-aminophenol) (POAP) has been successfully synthesized by mechanochemical solid state polymerization (MCSSP) as a green method which is simple, rapid, free hazard solvent, economically route and environmental friendly method. POAP has been synthesized by using developed Mortar Grinder RM200 without using solvents in the preparation process and has been compared with the POAP synthesized by interfacial polymerization method (IP) as traditional method. The comparison between the two techniques was carried out by justifying various analyses such as, Fourier transform infrared spectra, ultra violet visible spectra (UV-Vis), X-ray diffraction, thermogravimetric analysis, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX). The analysis revealed that there is a good agreement between the MCSSP and IP method to synthesize POAP. POAP synthesized by MCSSP method has nearly the same high crystallinity of POAP synthesized by IP method. The energy band gap (Eg) was detected for POAP solution (DMF) synthesized by the two methods. Eg was found to be 1.74 eV and 1.95 eV for POAP synthesized by MCSSP and the IP method respectively. A thin film of POAP either synthesized by MCSSP or IP method was fabricated. Morphological and optical properties of the thin film have been investigated using SEM/EDX, AFM, and UV-Vis test. POAP thin filmwas located in the semiconductor materials range. (C) 2017 Elsevier Ltd. All rights reserved.