An automated experimental apparatus was build to study the PSA oxygen enrichment process. Mass flux and concentration of all streams connected to the adsorption bed were continuously monitored so that the transient behavior of the process could be examined. In particular, a four-step process operated under various production, pressurization, and blowdown rates was studied in detail. The experimental data were then compared with the simulation results of a simple, isothermal model. The adsorption isotherm and the mass-transfer rate constants used in the model were taken directly from literature data. The simulated and the experimental transient results were in reasonable agreement when the purge step was long, but for cases with a short purge step, a slower than predicted desorption rate was observed. The thermal effects not considered in the model were believed to be responsible for this difference.