Abstract
The relativistic theory developed by previous authors for the spectral profile of a Thomson scattered wave is applied to the highest temperatures expected from currently planned fusion machines (25 keV). Adequate procedures for data reduction and error analysis are described and applied to experimental results collected on TFR. These computations yield corrected temperatures and error bars which differ already considerably from those obtained by the usual procedures. The temperatures are as much as 35 per cent lower, and the errors 50 per cent less, than the corresponding classical values.