This study investigates the mechanical properties of monolayer MoS₂, a two-dimensional semiconductor. Single and bilayer MoS₂ were exfoliated from bulk crystals and transferred to a substrate with microfabricated circular holes. The suspended membranes were deformed and eventually broken using an atomic force microscope (AFM). The in-plane stiffness of monolayer MoS₂ was found to be 180 ± 60 N m⁻¹, corresponding to an effective Young’s modulus of 270 ± 100 GPa, comparable to that of steel. Breaking occurred at an effective strain between 6 and 11%, with an average breaking strength of 15 ± 3 N m⁻¹ (23 GPa). The strength of the strongest monolayer membranes was 11% of its Young’s modulus, indicating highly crystalline and defect-free material. These results suggest that monolayer MoS₂ could be suitable for applications such as reinforcing elements in composites and flexible electronic devices.This study investigates the mechanical properties of monolayer MoS₂, a two-dimensional semiconductor. Single and bilayer MoS₂ were exfoliated from bulk crystals and transferred to a substrate with microfabricated circular holes. The suspended membranes were deformed and eventually broken using an atomic force microscope (AFM). The in-plane stiffness of monolayer MoS₂ was found to be 180 ± 60 N m⁻¹, corresponding to an effective Young’s modulus of 270 ± 100 GPa, comparable to that of steel. Breaking occurred at an effective strain between 6 and 11%, with an average breaking strength of 15 ± 3 N m⁻¹ (23 GPa). The strength of the strongest monolayer membranes was 11% of its Young’s modulus, indicating highly crystalline and defect-free material. These results suggest that monolayer MoS₂ could be suitable for applications such as reinforcing elements in composites and flexible electronic devices.