This study examines the utility of applying the cause-and-effect analysis (CEA) technique to the investigation of the structure and properties of mathematical models of geophysical phenomena. The principal rules of the CEA technique are presented, and their use is illustrated by application to four formulations of the Chapman photochemical cycle for ozone. The CEA shows not only the sensitivity of these models but also how their variables interact to produce this sensitivity. It is therefore concluded that the CEA technique is a potential powerful tool for the intercomparison of a wide variety of mathematical models of geophysical phenomena. ¿ American Geophysical Union 1991