It is a major challenge to transform a laboratory scale production of fuel cells to an industrial scale in terms of throughput, operating lifetime, cost, reliability and efficiency. In spite of a number of efforts, the durability, reliability and cost of fuel cells still remain major barriers to scaling-up and commercialization. Unless these challenges are fully understood there is little chance of overcoming them. In fact, though much fundamental research has been performed, there is still no clear understanding of both the theoretical solution and technical measures needed to solve the durability and performance degradation of fuel cells in the scaling-up process. In this critical review, we will revisit advances in theory of flow field designs. Then, we will analyze main issues and challenges in concepts and criteria of flow field designs and development of theoretical models. We will focus on uneven flow distribution as a root cause of low durability and reliability and performance degradation and why flow field designs are a strategic solution to integrated performance, flow conditions, structure and electrochemical processes. Finally, we will discuss criteria and measures to tackle uneven flow distribution as well as critical durability and performance degradation in the scaling-up of fuel cells. (C) 2015 Elsevier Ltd. All rights reserved.