This study is aimed at verifying the reliability and reproducibility of combustion tests, including ignition, load change and fuel changeover, conducted at a well-resourced fullscale gas turbine syngas combustion test facility. The 10 MWth, single-can, syngas-fired combustion test facility was equipped with analytical equipment to measure air and fuel flow rates to the combustor, the metal/gas temperature in the combustor, and exhaust gas composition and temperature distribution at the combustor's outlet. To confirm the test facility's reliability, the repeatability of the fuel changeover test from natural gas to syngas was evaluated. Reliability was also verified by cross-validating the theoretical and measured values for fuel/air (F/A) ratio and Turbine Inlet Temperature (TIT). In this study, the deviation between the averaged F/A ratio based on O-2 and CO emission data and the F/A ratio based on the mass flow rate was under 2% at most, when the F/A ratio exceeded 20%. And, the calculated TIT for syngas, taking thermal dissociation and heat loss into consideration, correlates well with the experimental result which is the corrected TIT value based on heat balance at the temperature sensor tip. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.