Superconducting YBa2Cu3Ox materials were produced by the FQMG method and their microstructures were defined by XRD analysis and optical microscopy. The optimum growth temperature and time were estimated by XRD and resistivity measurements to be 1050 degrees C, which is in the range of the peritectic temperature of the YBCO system, and over 10 h, respectively. The effects of increasing Ag addition and applied magnetic field on the microstructure and physical properties of this system were investigated. It was found that the critical temperature (T-c,T-zero) of specimens slightly increased on increasing the Ag content up to 20 wt.% and the transition curves broadened on increasing the magnetic field. Additionally, the effect of oxygen annealing on the Ag-added specimens was examined and the curves of resistive transitions became sharper and T-c,T-zero significantly increased. (C) 1998 Elsevier Science S.A. All rights reserved.