Particulate matter emitted as fly ash from municipal refuse and sludge incineration operations consists largely (>90 percent) of inorganic species, including soot. Although commonly these inorganics are referred to as oxides, it is evident from the compositions of the waste being combusted that chlorides, sulfates, and, in the case of sludge, phosphates are potential reactant products in the combustion process. This report presents a brief summary of existing data on the composition of ashes resulting from various municipal refuse and sludge incineration operations and new data as to the inorganic compounds present. Several samples of stack emission fly ash were collected and analyzed in detail for their elemental contents in order to provide insight as to the potential inorganic compounds possibly present. Then compound identification work was performed by X-ray diffraction (XRD) and Fourier Transform infrared (FT-IR) techniques. The compound analyses showed the presence of many inorganic compounds in addition to oxides in the fly ashes. The use of the FT-IR technique is detailed in the report because its application to inorganic species identification is relatively new.