This paper experimentally investigated the thermal performance of the developed solar box cooker with different reflector configurations. All tests were carried out under Bahir Dar (Ethiopia) prevailing weather condition. Two standard tests, namely stagnation test and sensible heat test were adopted in order to evaluate the thermal performance of the cooker. The highest maximum plate temperature of 148.7 degrees C can be achieved by the cooker with tracking reflector at optimal angle. In order to evaluate the performance of the cooker, the following performance indexes were employed, thermal efficiency, cooking power and two figures of merit, namely the ratio of optical efficiency to heat loss factor (F-1) and the product of heat exchange efficiency factor and optical efficiency (F-2). According to the experimental data, the highest computed value F-1 of 0.154 degrees Cm-2/W, can be obtained from the cooker with tracking reflector at optimal angle. The thermal efficiencies achieved by Cooker I, II and III are 37.24%, 32.27% and 33.89%, respectively. Thermal efficiency of the cooker was improved by 9.6% by tracking reflector at optimal angle instead of with fixed reflector. Furthermore, the thermal efficiency was also improved by 15.4% by using aluminum cooking vessel in place of using stainless steel vessel. It can be concluded from the experiments that effective utilization of all solar radiation intercepted on the reflector, and the use of cooking vessel having a reasonably good thermal diffusivity contribute significant roles to Improve the cooking performance of the cooker.