The Department of Energy has initiated a program to investigate the potential for coal-water mixtures to serve as direct substitutes for liquid petroleum and natural gas in combustion processes. As a part of this overall DOE effort, the Morgantown Energy Technology Center is investigating the feasibility for the combustion of ultra-clean, coal-water mixtures (UCCWM's) in gas turbines. A necessary goal of this program is to develop an understanding of the chemistry of the products of combustion (POC) of UCCWM's. Both experimental and modeling efforts are in progress to investigate POC chemistry. Based on these results, specifications for a UCCWM turbine fuel can be developed. Initial tests to characterize the POC from UCCWM were performed in an atmospheric combustion rig. This pilot-scale experimental combustion rig, configured to provide a high degree of combustion efficiency, was designed and constructed at METC to simulate the primary characteristics of combustion in a gas turbine combustor. The characterization of POC from UCCWM's was accomplished by on-line and extractive techniques. These measurements include gas composition, alkali levels, POC particle mass loading and size distribution, and complete chemical and physical characterization of the POC particles. A POC slipstream taken isokinetically from a plug flow region immediately downstream of the combustion zone provided the necessary samples for analysis. In addition, a water-cooled probe provided particulate and gaseous samples from various locations within the combustion zone. These data provide information on the rate of particle burnout and uniformity of combustion within the flame. POC data generated from this combustion rig and the general impact of the turbine performance are presented in this paper. 6 figures, 4 tables.