Terahertz (THz) devices and applications are recently gaining much attention due to the increased availability of THz sources. Still, the THz dielectric properties of common materials that are extensively characterized at microwave frequencies, are rarely reported in the literature. Recently, we characterized high-permittivity Rogers substrates by means of THz time-domain spectroscopy measurements in reflection mode. Here, we briefly discuss the versatility and accuracy of the employed technique for the characterization of various dielectric materials extensively used in fabrication processes. Experimental results are provided for a common dry resist (Ordyl) film showing remarkable agreement.