Judging by a literature survey the data presented in this paper are the first that have been obtained from a continuous and comprehensive instrumented study of transient cargo effects in a ventilated ship's hold. The data may serve three purposes:To provide basic information of value in establishing operating procedures for marine cargo ventilation.To assist the air conditioning designer in evaluating loads when a ship's hold is to have controlled temperature and humidity.To assist thermal engineers concerned with warehouses to more accurately evaluate the effect on stored material of transient environmental changes. After all, a moving ship's hold which undergoes a complete periodic change from cool-to-hot-to-cool outside conditions over a period of 25 days is in many respects analogous to a stationary warehouse which may be subject to the same cycle, but over a 365 day period.