Numerical values of thermal diffusion factors are a prerequisite for the discussion of thermal diffusion columns. They can be calculated by theory using the Lennard-Jones 612 model and appropriate force constants. The validity of theory at low concentrations has been proved in few cases only. A two-bulb technique has been applied here to measure a(T) of the systems Xe-He, Xe-H2, Xe-D2, Xe-Ne, Xe-N2 and Xe-A in the temperature range of 300700K. Radioactive 133Xe was used as a tracer. Our experimental results show that the quantitative agreement between theory and experiment is good. In the case of Xe-H2, Xe-D2 and Xe-N2 the measured thermal diffusion factor is larger than the predicted thermal diffusion factor by 510%. The limiting value of RT is about 0.50 for our systems which is definitely smaller than RT-values of 0.65 that have been previously measured in aequimolar mixtures of Xe-He, Xe-Ne and Xe-A. The accuracy of our measurements is mainly limited by the corrections implied in the Geiger-Mller counting technique and is of the order of 5%.