This paper presents a study on a novel instrumentation system for the measurement of temperature distribution of combustion flames. This system operates upon the three-color principle combining advanced optical sensing and digital image processing techniques. It comprises an endoscope, a light splitter assembly, a CCD camera, a frame-grabber and associated software. This system was calibrated using a blackbody furnace as standard temperature source. The relationship between flame temperatures and grey-level of the images was established through image processing and function correlation. Experimental results obtained on a gas-fired combustion rig provide flame images and temperature distributions on three different wavelengths. Based on the flame temperature distribution the combustion conditions can be analyzed. Experimental results also reveal that this system is capable of online measurement of temperature distribution in a combustion zone. This system can potentially be applied to many areas such as power generation, metallurgy, chemical engineering. It is also a powerful tool for improving the control of combustion process. This paper presents a study on a novel instrumentation system for the measurement of temperature distribution of combustion flames. This system operates upon the three-color principle advanced optical sensing and digital image processing techniques. It includes an endoscope, a light splitter assembly, a This system was calibrated using a blackbody furnace as standard temperature source. The relationship between flame temperatures and gray-level of the images was established through image processing and function correlation. Experimental results obtained on a Based on the flame temperature distribution the combustion conditions can be analyzed. Experimental results also reveal that this system is capable of online measurement of temperature distribution in a combustion zone. This system can potentially be applied to m any areas such as power generation, metallurgy, chemical engineering. It is also a for tool for improving the control of combustion process.