The spectral radiant flux of six commercial high power LED packages from two manufactures has been measured with a custom made integrating sphere at different junction temperature, ranging between 290 and 340 k. A spectrum model for one particular temperature (300k) has been constructed. Afterwards,the variation in all initial modeling parameters with junction temperature has been examined.In contrast with a number of merely mathematical spectrum models proposed in literature,the Boltzmann exponential behavior with carrier temperature variation,the band gap energy shift and the decrease in the nonradiative recombination rate with junction temperature have been included explicitly.Very high coefficients of determination have been found,indicating a good agreement between the model and measurement data.For AlGaInP-based LEDs could be distinguished from the values obtained for InGaN-based emitters.The model has been validated by comparing flux and color coordinates of measures and simulated spectra at 340 k junction temperature. Except for one LED showing a spectrum deficiency,flux and color deviations between measurement and simulation have been found to be lower than 2.5/ and smaller than the radius of a three-step MacAdam ellipse,respectively.In practice,only two spectral flux measurements are needed to accurately simulate a single color spectrum at any temperature.