We report nondestructive measurements of the properties of two-component epoxy adhesives at THz wavelengths using a reflective time-domain spectroscopy system. We describe a simple method to determine the refractive index, layer thickness, and absorption coefficient using time-domain data applying a Fresnel-equation based approach. The results indicate that the adhesive’s curing process may be monitored using a simple parameter extraction technique based on time-domain measurements for systems featuring small bandwidth, showing good agreement with data obtained with from transmission measurements.