Studies aimed at designing new allotropic forms of carbon have received much attention.Recently, a new 2D graphene-like allotrope named Pentahexoctite was theoretically proposed.Pentahexoctite has a metallic signature, and its structure consists of continuous 5-6-8 rings of carbon atoms with sp 2 hybridization. Here, we carried out fully-atomistic computational simulations, combining reactive (ReaxFF) molecular dynamics (MD) and density functional theory (DFT) methods, to study the elastic properties and fracture patterns of Pentahexoctite monolayer. Results revealed a Young's Modulus of 0.74 TPa, smaller than the graphene one (about 1.0 TPa). The Pentahexoctite monolayer, when subjected to a critical strain, goes directly from elastic to completely fractured regimes. This process occurs with no plasticity stages between these two regimes. Importantly, graphene presents a similar fracture process.The elastic properties calculated with both DFT and MD are in good agreement.