The equilibrium geometry and harmonic frequencies of the 6-methylnicotinic acid, were determined and analyzed at DFT level employing the basis set 6-311+G(d,p). The skeleton of the optimized molecule is non-planar. In general, a good agreement between experimental and calculated normal modes of vibrations has been observed. The molecular electrostatic potential surface has been used along with frontier orbital energy gap, electric moments, first static hyperpolarizability, to understand the activity of the molecule.