A study of antimony yellow in the system, PbO-Sb2O5-SnO2 was made by X-ray analysis and spectroreflectance measurements. Seven compositions were tried for investigation at temperatures ranging from 7000C to 1100°C and the results indicated that the antimony yellow containing tin oxide is the solid solution of pyrochlore type having the general formula A2B2O7 or M4O7.