Firstly, the efficiency of each chemical treatment was con-firmed by FTIR. shows the FT-IR spectra of GS, ATGS, BGS and cellulose nanocrystals from garlic straw (CNC-GS). FT-IR spectroscopy, which is a complementary method, yields information about chemical composition, molecular conformation and hydro-gen bonding patterns of the cellulose allomorphs . The peak near 1640 cm−1 was attributed to absorbed water in the cellulose . Although the peak at 1630 cm−1in GS, ATGS and BGS might be caused by the presence of water, it would be more probably attributed to the aromatic C= C stretch of aromatic rings of lignin . The contribution due to the absorbed water clearly predominated in the case of CNC-GS. All the spectra were characterized by a dominant O-H stretch band (3406–3420 cm−1) and a C H stretch band (2897–2923 cm−1) corresponding to the aliphatic moieties in polysaccharides. The absorption band at 1118 cm−1 was attributed to C OH skeletal vibration. The C – O - C pyranose ring skeletal vibration gave a prominent band at 1048 cm−1. A small sharp band at 904 cm−1 represented the glycosidic C1-H deformation with ring vibration contribution and OH bending, which is characteristic of b-glycosidic linkages between glucoses in cellulose. The growth of intensity of these peaks match with the increase in the percentage of cellulosic components. The differences in the spectra of BGS and CNC-GS confirmed that this sample had higher cellulose content.