High temperature superconductors in the form of coated conductors, made from REBa2Cu3O(7-x) (RE = rare earth element) are playing an increasing role in the fabrication of magnets and the development of high current and high field applications. For these purposes high critical current densities Jc and good magnetic properties homogeneous over the full length (hundreds of meters) of the tape are necessary. This thesis presents results of in situ magnetization and Ic reel-to-reel measurements in several tapes of REBCO coated conductors from Superpower Inc. with lengths of more than 100 m. Reel to reel measurements enable continuous critical current Ic(x,B,theta) evaluations of superconducting tapes for commercially available lengths of superconducting tape with very high resolution. Further, an array of Hall probes was installed for magnetization measurements and contact free observation of the current flow, which provide a reliable and very fast, but non-calibration free opportunity for the analysis of long tapes. We made detailed comparisons of those two methods. Our results confirm the validity of the magnetization method to find inhomogeneities. The possibility of identifying defects in tapes is crucial for the construction of magnets, since a single defect degrades the performance of the whole magnet. Up to now these non-destructive measurements were made at liquid nitrogen temperature. We developed a measurement setup for reel-to-reel Hall probe measurements at liquid helium temperature. Such measurements are unique at present. This temperature range is interesting, because the construction of all-superconducting magnets for generating fields above 30 T requires cooling to 4.2 K. While coated conductors are widely characterized at 77 K, the flux pinning mechanisms are poorly known at temperatures below Tc/2. These mechanisms may be very different at high and low temperatures. Because of the strong reduction of thermal fluctuation effects weaker flux pins are becoming more important at low temperatures.