Transient combined conductive-radiative heat transfer is analyzed in an optical quality glass disk. Typically semitransparent materials such as a glass have spectrally selective absorption and emission characteristics. In the present analysis the spectral dependence of the absorption coefficient on wavelength is appropriately accounted for, and discrete ordinates method is used to solve the radiative transfer equation for the axisymmetric cylindrical geometry. Specularly reflecting boundaries are considered, and Fresnel＇s equations are used to predict the spectral radiation characteristics at the interfaces. The numerical analysis is validated by comparing predictions to the experimental results for soda-lime glass. As an example, BK7 optical quality glass is considered as a semitransparent medium.