This paper explores the merits of a recently proposed 2D material, the B4C3 monolayer, for hydrogen storage by adsorption. The monolayer is decorated by Li to enhance adsorption. Density Functional Theory (DFT) is used to find the adsorption energy and electronic structure, while molecular dynamics runs to ensure the thermodynamic stability of the systems. The present study results show that a concentration corresponding to 3 Li atoms per unit cell is the optimal configuration for H2 storage, as it has good adsorption energy from -0.23 to -0.24 eV, the gravimetric capacity of 6.22 wt% within the requirements and desorption at room temperature. The current study outcomes concluded the conceivable utilization of the 3Li/B4C3 adsorptive medium for hydrogen storage applications.