Proton exchange membrane fuel cell (PEMFC), as a source of electrical power, provides numerous benefits such as zero carbon emission and high reliability as compared to wind and solar energy. The first part of this book attempt to model the voltage of PEMFC using simple and effective semi-empirical equations. The initial feature of the proposed technique is to incorporate the features of the mechanistic model with less complex equations. The second part of the book focuses on modelling the PEMFC temperature. The fault diagnosis procedure has also been elaborated for flooding and drying faults of PEMFC. Moreover, the electrical equivalent modelling has also been discussed all of the above-mentioned models consider ambient conditions changes directly.