New creep-resisting weld metals of P91 grade were manufactured by manual metal arc (MMA) process producing multi-bead multi-layer test coupons, from which specimens were taken for accelerated creep testing on Gleeble physical simulator. The recently developed accelerated creep testing (ACT) procedure on Gleeble allows transforming in a relatively short time (less than 100 h) the microstructure of creep-resisting materials to the near to thermodynamic equilibrium state, resembling that of multi-year application at creep condition. Such advanced transformation of microstructure in the investigated weld metals after ACT was confirmed by microscopic and microanalytical study. The results also appeared in agreement with Thermocalc calculations. By an optimum combination of chemical compositions of the electrodes with welding procedure and post-weld heat treatment, advantageous mechanical properties were achieved as well as results of ACT indicating potentially long creep life in service exposure conditions. In discussion of the ACT results, comparisons with results of conventional creep testing have been made. The ACT procedure appears useful in fast screening of newly developed creep-resisting materials.