Post-sintering treatments, such as zone melting under a thermal gradient, have been conducted on sintered YBCO tape cast films. YBCO precursor powder was derived through decomposition of a mixture of nitrates of cations in a microwave oven for similar to 4 min. The resulting powder was characterized and made into thin sheets by tape casting and then sintered at 945 degrees C for 5 h. The sintered tapes were subjected to repeated zone refining operations at the relatively high speed of similar to 30 mm h(-1). A microstructure having uniformly orientated grains in the a-b plane throughout the bulk of the sample was obtained by three repeated zone refining operations. Details of precursor preparation, microwave processing and its advantages, zone refining conditions and microstructural features are presented in this paper.