Cu-Nb composites are characterized by some special properties, which were discussed since a long time by many different authors [1, 2, 3, and 4]. For manufacturing linear accelerator units it is a great advantage that Cu-Nb don't form intermetallic compounds. One of the basic questions during application is the influence of the thermal expansion of copper and niobium. Thermal expansion of Cu-Nb was widely discussed by Nadeau and Ferrari [5]. Our research program consists of investigations on Cu50%-Nb50% composites and on Cu-Nb tubes, which on one hand have different textures and on the other hand the grain boundaries are much different in the composite with a curling microstructure and in co-extruded tubes. The present paper will concentrate on thermal stresses and the texture behavior in the temperature range 4K -1273K.