An experimental model of a photovoltaic (PV) module-proton exchange membrane (PEM) electrolyser system has been built. A model has been developed for each device separately based on the experimental results. Output current-voltage (I-V) characteristics of the PV module are modelled in respect to different irradiance and temperature conditions by experimental tests. Similarly, input I-V characteristic and hydrogen formation characteristic of the PEM electrolyser are measured and modelled. After these studies, combined PV module-PEM electrolyser system model is defined. There is a good agreement between model predictions and measurements. At 18-100% irradiance interval, operating points of PEM electrolyser on the PV module are predicted with relative errors of 0.1-0.8%. Furthermore, the study shows that these simple model system devices can easily be defined in MATLAB/Simulink and used to model similar systems of different size. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.