In this paper, a multi-stage stacked-tray solar seawater desalination still was designed and used to assess heat and mass transfer mechanisms and test water production performance in both transient and steady states. A mathematical model of heat and mass transfer was developed and used to calculate the heat transfer velocity equation at each stage, the heat and mass transfer equation at the highest stage, and determine the performance coefficient of the still. The running of the still only needs the solar energy. It is showed that the water production rate became stable after 3 h and higher temperatures resulted in higher water production rates. Both the performance coefficient in steady state and performance coefficient were above 1 when the temperature above 70 degrees C. Under the practical weather, the smaller the seawater depth was, the bigger the accumulative water production and performance coefficient were. The total production was 8.1 kg/m(2)center dot d and the performance coefficient was 1.12 when the depth of seawater was 2 cm. The good agreement between the model predictions and experimental data shows the validity of the model. (C) 2016 Elsevier Ltd. All rights reserved.