The study of the products of combustion continues to have real-world relevance since the primary cause of death in building fires is smoke inhalation, with the majority of deaths from carbon monoxide, CO, poisoning. An experimental study was conducted to examine upper-layer structure plus provide an initial characterization of a new compartment with a doorway. An additional study of the relationship between heat flux from external burning in a hallway and levels of carbon monoxide is also reported. Tests were conducted in a new ½ scale ISO compartment with a fully scaled doorway, using n-hexane pool fires within the center of the compartment. Upper-layer sampling at eight locations in the compartment has shown that the compartment upper-layer is relatively uniform in species mole fractions, yields, and temperature. Sampling in the front upper-layer of the compartment was performed for a series of experiments where the equivalence ratio was varied. Temperatures, species mole fractions, species yields, and doorway flows were found to have definite trends, which agreed with previous studies. The heat flux study utilized a reduced scale compartment with a separate inlet and an exit vent, which connected into the side of an attached hallway, forming an L-shape. For two cases of a deep and shallow hallway upper-layer a direct relationship between flames in the upper-layer and total heat flux was measured. High heat flux was found to only denote those areas were flames are present and is not related to the levels of CO present or oxidized in the hallway. / Master of Science