Recently, we have predicted a two-dimensional (2D) material named pentagraphyne (PG-yne); due to its intriguing properties, it is proposed for a wide range of applications. In this work, we have explored the potentiality of PG-yne as an anode material for Li/Na ion batteries using the density functional theory. Its differential adsorption energy suggests that maximal eight Li/Na ions can be accommodated over the PG-yne surface. We have obtained a high theoretical capacitance of 680 mAh g-1 for Li/Na ions adsorbed on PG-yne. The reported theoretical capacitance of PG-yne as an anode material in lithium-ion batteries (LIBs) is moderately higher than that of previously reported 2D anode materials, whereas PG-yne for NIB application has a significantly higher capacitance than that of several previously studied anode materials. Moreover, the low open-circuit voltage along with low diffusion barriers (<= 0.50 eV) and much higher electronic conductivity after the adsorption of Li/Na ions again suggest its applicability as an anode material. Further, the molecular transition rate study also confirms the faster diffusivity of Li/Na ions over the PG-yne surface. The high storage capacity and faster diffusion of Li/Na ions adsorbed on PG-yne are mainly due to the lightweight and unique atomic structure of PG-yne.