Minute quantities of phosphine were added to several cereal products and inert materials to investigate if temperature, duration of contact, and various aeration conditions would alter recovery. Previous experiments had shown that phosphine could diffuse through porous materials quite readily, so diffusion studies were also conducted at room temperature and elevated temperature conditions. Loss of added phosphine and poor recovery were shown to occur at elevated tempertures from systems containing cereal products or inert materials when proper precautions were not taken to insure an airtight system. Loss of phosphine was prevented and recovery greatly improved when an airtight system was used in the experiment.