The Pakistan Research Reactor was converted from 93% highly enriched uranium fuel to 20% low-enriched uranium fuel in October 1991. The reactor power was also upgraded from 5 to 9 MW. A series of critical and power experiments were performed on the new core for verification of design data and to determine the nuclear performance of the reactor. The characteristics tests included a criticality experiment, reactivity measurements on reflected and unreflected, critical and full-power cores, and flux distribution in and around the core, as well as thermal-hydraulic measurements. A comparison of the measured and the calculated results was also made. The results of the characteristics tests indicate that the performance of the new reactor is within design limits.