Swine manure mixed with sawdust was composted ina 205L pilot-scale vessel. Four runs with a total of 22 vessel studies were made during 1998 and 1999. Composting was conducted, with either continuous or intermettent aeration supplied to each veswsel, for 17-79 days. Temperature, airflow, carbon dioxide production, oxygen uptake, and ammonia production were monitored. Material masses, moisture content, pH and various chemical concentrations were determined for initial and final samples. Further in the final two runs, conndensate from the exhaust air stream from each vessel was collected using water cooled condensers. Consensates and extracts from initial and final samples were analyzed bt gas chromatograph with falme ionization detector for volatile fatty acids. The results indicvated airflow had a strong effect on emssions. Ammonia showed a linear trend versus airflow, with about 50% reduction in ammonia occurring for a 75% reduction in airflow. Thus, there is a potential for reduced odors with reduced airflow. Reults also indicate that pH influenced the onset of composting and the potential for odour release. For vessels that started at higher pH values, development was much mopre rapid. These effects, combined with that fact that a significant majority of volatile fatty acids initially present at the ennd of runs, indicated that high bacterial activity was important for reduction of odour potential.