The research project was initiated with the principle objective of evaluating the oxygen transfer perfomance of various generic aeration systems used in activated sludge wastewater treatment. A secondary objective of the project was to evaluate various oxygen transfer data analysis methods in current use. Results of the work indicated that, of the systems tested, fine bubble diffusion equipment transferred oxygen most efficiently in clean water. Results also indicated that, in clean water, jet aeration equipment transfers oxygen more efficiently than do coarse bubble aeration systems. However, because the value of wastewater correction factors (alpha and beta) are dependent on the type of aerator tested, the relative performance of the aerators to one another in wastewater may be different.