A dynamic electrochemical simulation model of a grid independent proton exchange membrane (PEM) fuel cell power plant is presented. The model includes the methanol reformer, the PEM stack, and the power conditioning unit. The model is then used to predict the output voltage and study the transient response of a PEM power plant when subjected to rapid changes in a residential load connected to it. The results show the fast response capabilities of the PEM power plant in following changes in the load. (C) 2004 Elsevier B.V. All rights reserved.