Data from experiments measuring the rate of uptake and elimination of nonmetabolic gas in living organs are usually analyzed by several exponential time constants or their equivalent half-times (i.e, exponential series analysis). To avoid the limitations of this technique, we have formulated a method that combines analysis by moments of distribution with transfer function techniques, which makes the analysis independent of any mechanistic model. This method is an improvement over previous methods because it allows better comparison of gas exchange experiments and better prediction of gas exchange in the formulation of diver decompression schedules. Measurements of radioxenon uptake and elimination in two areas of a dog are presented. Analysis of the same organ response by both methods showed a fivefold variation in derived exponential time constants compared with less than 10% variation among moment descriptors.