In this research, we have investigated through the first principal calculations the adsorption of hydrogen molecule on AlC3 monolayer. In the beginning, we determined the most stable positions of hydrogen molecule adsorption on AlC3 substrate. The calculations indicate that the position of greatest stability is in the center of the carbon atom hexagon when the hydrogen molecule is placed perpendicularly on AlC3 surface, and the adsorption energy Eads is near to −0,2189 eV, where the most stable distance is 2.50 Å. The hydrogen molecule adsorption at various positions on AlC3 surface maintains its semiconducting character. The examination of the diffusion paths between the various sites indicates an ability of the hydrogen molecule to migrate between the sites, which are spaced by a slight energy barrier of 0.0163 eV. It is shown that AlC3 monolayer possess the ability to adsorb 16 hydrogen molecules, with 11.8 wt% as gravimetric capacity, as well as a desorption temperature of 173.35 K. Based on the findings, the AlC3 monolayer may be a promising candidate for hydrogen storage.