This work provides a framework for predicting fracture of catalyst coated membrane (CCM) due to coupled electro-chemo-mechanical degradation processes in proton exchange membrane water electrolysis (PEMWE) cells. Electrolysis in the catalyst layer (CL) bulk, diffusion of Hydrogen proton through the membrane (MEM), and mechanical compression at the interface with the porous transport layer (PTL) generate micro-cracks that influence the catalyst degradation. Based on our experimental observations, we propose a new theoretical formulations along with the constitutive framework to help understanding and providing a reliable description of the stated multi-physics problem. The computational modeling of crack formation in the CL bulk is achieved in a convenient way by continuum phase-field formulations to fracture, which are based on the regularization of sharp crack discontinuities. The model performance is demonstrated through two representative boundary value problems, representing the cell setup and working of the PEMWE cell.(c) 2022 Elsevier B.V. All rights reserved.