In this study, we comprehensively analyze the probability distribution of the hydrogen production for PV assisted PEM electrolyser system. A case study is conducted using the experimental data taken from a recently installed system in Balikesir University, Turkey. A novel computational tool is developed in Matlab-Simulink for analyzing the data. The concept of probability density frequency is successfully applied in the analyses of the wind speed and the solar energy in literature. This study presents a method of applying this knowledge to solar energy assisted hydrogen production. The change in the probability distribution of the hydrogen production with the solar irradiation throughout a year is studied and illustrated. It is found that the maximum amount of hydrogen production occurs at between 600 and 650 W/m(2) of solar radiation. Annual hydrogen production is determined as 2.97 kg for per m(2) of PV system. Average hydrogen production efficiency of the studied PEM electrolyser is found to be 60.5% with 0.48 A/cm(2) of current density. The presented results of this study are expected to be valuable for the researchers working on renewable hydrogen production systems. Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.