This paper reports an extensive spectroscopic study of the fluorescence of pyrromethene 597-8C9, which can be used as a dye in two-colour laser-induced fluorescence thermometry. This technique requires a single dye and two spectral bands of detection to measure the droplet temperature. The selection of a fluorescent tracer is a critical issue. To achieve measurements with a reasonable accuracy, a tracer should exhibit a fluorescence spectrum that is particularly dependent on the temperature. Another important feature is the possibility of using the same dye and the same optical components with a large variety of fuels, including multi-component fuels which are commonly used in industrial applications, which was not possible with usual tracers like rhodamine B. This paper demonstrates that pyrromethene 597-8C9 is relevant for measuring the temperature of droplets made of alkanes (dodecane), ketones (3-pentanone) or alcohols (ethanol). It can also handle mixtures of ethanol and 3-pentanone. In this study, demonstration experiments are performed on droplets injected into a hot air chamber (645 K).