Steam explosion technique was used to isolate banana fibrils from banana fiber. The surface polarity of banana fiber, banana fibril, and chemically-treated banana fibril was investigated by ultraviolet/visible spectroscopy using solvatochromic probe dye molecules. The empirical Kamlet-Taft solvatochromic polarity parameters such as hydrogen bond donating ability HBD (alpha), hydrogen bond accepting ability HBA (beta), the dipolarity (pi*), Gutman acceptor number, and Reichardts ET(30) values for the banana fiber, banana fibril, and chemically-treated banana fibril were determined. It was observed that banana fibril has higher HBD value than banana fiber. Chemical treatment of the banana fibril has lowered the HBD value. The results of the empirical polarity parameters determined were found to be consistent with the results of electrokinetic measurements. The functional groups on the surface of banana fiber, banana fibril, and chemically-treated banana fibril was further analyzed using Fourier transform infrared spectroscopy (FTIR). FTIR spectra revealed the dissolution of the various components from the banana fiber after steam explosion which was further confirmed by scanning electron microscopy.