The resistive transitions of large grained and textured YBa2Cu3O7-x polycrystals fabricated by the flame-quench-melt growth (FQMG) process were studied in various selected magnetic fields. It was found that the appropriate amount of silver addition enhances the formation of the superconducting phase and slightly increases the transition temperature. The magnetic behaviour of YBCO with silver and without silver were determined by measurements of the resistivity (rho) in an external magnetic field. It was found that samples with silver showed a lower transition temperature in a magnetic field. The activation energy, U-0, for thermally activated flux flow (TAFF) was estimated for all samples from the slope of the Arrhenius plot of In rho versus T-1. It was found that the activation energy of the samples decreases with increasing silver content and magnetic field. (C) 1998 Elsevier Science S.A.