Surface electronic structure and isotropic superconducting gap in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>(</mml:mo><mml:msub><mml:mi>Li</mml:mi><mml:mrow><mml:mn>0.8</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>Fe</mml:mi><mml:mrow><mml:mn>0.2</mml:mn></mml:mrow></mml:msub><mml:mo>)</mml:mo><mml:mrow><mml:mi>OH</mml:mi><mml:mi>Fe</mml:mi><mml:mi>Se</mml:mi></mml:mrow></mml:mrow></mml:math>

To understand the pairing symmetry and superconducting transition temperature in heavily electron-doped iron-based superconductors, it is important to study more of these materials, especially ones with decent stability in air and without phase separation. Here, angle-resolved photoemission spectroscopy probes the surface electronic structure and superconducting gap in the new superconductor (Li${}_{0.8}$Fe${}_{0.2}$)OHFeSe, which shows a ${T}_{c}$ as high as 40 K.