Quantification of physical properties of fossil fuel fired flames is becoming increasingly important to achieve in-depth understanding and subsequent optimisation of combustion processes. This paper presents investigations into the geometrical and luminous properties of pulverised coal flames using an advanced flame monitoring system. The system combines optical sensing, digital image processing and computing techniques and is designed to measure most physical parameters of a flame. Experimental trials of the system have recently been conducted on a 1 MWth coal-fired combustion test facility. The flame in the furnace was visualised continuously using the imaging system and then characterised in terms of geometrical and luminous parameters. Results obtained over a range of combustion conditions demonstrate that the system is capable of characterising the flames both qualitatively and quantitatively. The correlations between the flame parameters measured and the corresponding furnace data, including furnace load, mass flow rate of primary air and particle size, are identified and analysed.