Surfaces treated with a ceramic roof coating (CRC) marketed as AZTEC No. 100 were compared to untreated and white painted surfaces. Dry-bulb and black globe temperatures in the space below or behind the surface were the criteria for comparison. Comparisons included small horizontal panels with open sides, small unvented galvanized steel and styrofoam boxes, and an open-side steel poultry building. The CRC was effective in reducing temperatures in the enclosed test boxes, but less effective with open-side test panels and the open-side steel building. Tests also indicated the CRC is characterized by high emissivity (0.95) and reflectivity (0.87). The evidence indicates the CRC would be most effective with uninsulated, enclosed metal shell buildings, but ineffective with insulated and open-side or well ventilated buildings.