Channeling is an operational problem of updraft gasifiers used to gasify cereal straw. Airflow distribution within a fixed straw bed before the initiation of gasification was investigated to understand the channeling. Absolute pressure deviations in the central plane of the straw bed were determined to check the uniformity of airflow distribution, because pressure was the driving force of airflow. Airflow channeling occurred through the straw bed even before the initiation of gasification. Superficial velocity through the straw bed inversely affected the uniformity of airflow distribution while machine-chopped straw and straw bed depth improved it.