Detailed infrared spectrum in gas phase, NMR spectra analyses and theoretical studies of 2-amino-3-methylbenzoic acid were performed with DFT/B3LYP/6-311G+(2d,p) level of method in Gaussian 09W. Ground state molecular geometries of monomeric and dimeric structures were calculated in vacuum and compared to the experimental XRD results. Potential energy surface graphics of the proton transfer and torsional tautomerism process were obtained. Also, HOMA aromaticity chancing graphics were drowned in mentioned process. The IR band assignments and the decompositions of potential energy for each band were done using theoretical calculations. 1 H and 13 C NMR chemical shifts analyses were performed by using GIAO NMR calculations with SCRF solvent model.