This work measures the temperature of CO2 flows inside a micro-channel by applying a Laser-Induced Fluorescence (LIF) thermometry technique with a single-dye method. A temperature-sensitive Rhodamine 6G (Rh6G) fluorescent dye was used as a tracer of the CO2 flow. The temperature as a function of the fluorescence intensity calibration curve for only Rh6G was estimated for temperatures ranging from 22 °C to 52 °C. Initially, the experiments were conducted at a specific temperature and a range of pressure of CO2 and Rh6G mixture to observe the effect of pressure on the temperature sensitivity of the Rh6G dye. The temperature of the CO2 flowing inside the micro-channel was measured using the calibration curve and pressure effect observations. These measured temperatures can be fed into an equation that calculates the heat transfer coefficients (HTCs) of CO2 flow.