This work has as its objective to evaluate the effect of mold flux waste incorporation in a red ceramic body. The mold flux waste came from an industry of additives for continuous casting of steel, in the municipal area of Guaratinguetá, State of São Paulo, Brazil. Initially, the mold flux waste was characterized in terms of chemical composition, particles size distribution, X-ray diffraction, specific surface area and scanning electron microscopy. Clay mixtures were prepared with additions of 0, 5, 10 and 20 wt.% of mold flux waste. Red ceramic specimens were produced by extrusion and then fired in an industrial furnace at 750, 850, 950 and 1050 ºC. Some physical and mechanical properties were evaluated. The results indicated that mold flux waste addition optimized the plasticity of the clayey body, increased the flexural and compressive strength and reduced the values for water absorption. The specimens with 5 wt.% of mold flux waste, at 1050 ºC firing temperature, presented the best results for the properties evaluated, indicating a higher packing for this composition. The incorporation of mold flux waste allowed improvements in the clayey body, producing better quality materials and being an appropriate way of disposal. Keywords: Clay, Incorporation, Red ceramics, Mold flux, Waste