Surface reactions of atomic and molecular nitrogen (N-2) with liquid group III metals: Al, Ga, and In has been investigated by quantum mechanical calculations in density functional theory (DFT) formulation, using cluster representation of metal surface. It has been shown that the N-2 molecule dissociates during adsorption on the surfaces of liquid group III metals. The N-2 dissociation energy barriers are equal to 3.0 eV, 3.4 eV, and 3.6 eV for Al, Ga, and In, respectively. They are much smaller that the dissociation energy of free N-2 molecule, equal to 9.76 eV. It has been also determined that the adsorption of N-2 on surface of liquid Al is an exothermic and on Ga and In is an endothermic process. These results are consistent with experimentally observed combustion of liquid Al in high pressure of nitrogen and the absence of combustion of both Ga and In. The process of dissolution of N atoms adsorbed on liquid Al surface has been also analyzed. The energy barriers for the direct jump of the N adatom from the surface position into the liquid Al interior is equal to 1.3 eV. This suggests that the dissolution of N in liquid Al proceeds not by direct jumps of N adatoms into the liquid interior but by Brownian motion of clusters consisting of these adatoms and neighboring Al atoms. The results of the calculations indicate that nitrogen solution in liquid group III metals consists of single N atoms strongly attached to the surrounding Me atoms.