Wood pellets emit gases such as CO, CO2 and CH4 during storage especially under high temperature conditions. This study investigates the stratification of the evolved gases in a sealed storage container of 1.2 m diameter and 4.6 m height. The data recorded include the concentration of off-gasses (CO2, CO and CH4), temperature and relative humidity profiles in vertical and horizontal directions. The results obtained clearly show high concentration of gases as well as fast depletion of oxygen. The emitted gases showed to have higher emission factor compared to work done with white wood pellets in small scale. Some stratification was observed for CO2 and CH4 over the first days of storage. However for CO the stratification was much clear and related to high uptake of CO by wood pellets over time. (C) 2014 Elsevier Ltd. All rights reserved.