An investigation was undertaken to examine the performance of a Fresnel reflection sensor (FRS) incorporated into a differential scanning calorimeter (DSC) to track the cross-linking of epoxy resins. The initial design used a micrometer translation stage to lower the FRS through an orifice in the DSC platinum lid and onto the pan containing the sample. During exothermic cross-linking experiments, the resin refractive index and the heat evolved were measured simultaneously, allowing for direct comparison between the data. Combining the two measurement techniques produced a powerful hyphenated analytical procedure that demonstrated the feasibility of using the FRS for in-situ cure monitoring of epoxy resin systems. During the cross-linking of specified resins, the sensor revealed optical phenomena throughout the latter stages and was shown to be sensitive to the glass transition temperature, nano-particulate movement, nano-particulate concentration and phase separation. Therefore, the introduction of the FRS to the DSC provided valuable cross-linking information. A second modification to the DSC permitted the accommodation of an optical fibre probe, which facilitated simultaneous DSC/FRS/Fourier transform infrared spectroscopy (FTIRS) analysis. Good correlation between the cross-linking kinetics of an epoxy resin system was demonstrated using the hyphenated techniques and hence alleviated the issues of cross-correlation between individual experiments.