Carbon/carbon composites (CCC) contain an ablation resistant carbonaceous matrix reinforced with high strength carbon fibers. This combination leads to high thermal stability allowing CCC to be used as thermal protection systems. CCC are manufactured through time intensive and costly densification processes called chemical vapor deposition (CVD) and polymer infiltration and pyrolysis (PIP). Therefore, there is a need to reduce processing costs for CCC. PIP has potential to reduce costs by using a polymer with a high carbon content and a carbon with an open pore structure when pyrolyzed. In order to meet these demands, the pyrolysis conditions must be tuned. However, the polymer’s thermal decomposition needs to first be understood. In this study, the char and pore structure formation of a high char yielding furan-based epoxy resin was investigated from 200-1000 °C. Thermogravimetric analysis with mass spectrometry (TGA-MS), Fourier-Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, and Scanning Electron Microscopy (SEM) were used. Three major decomposition regions were identified showing how the carbon and pores formed. The first region showed the beginnings of porosity and polyaromatic carbon domains. The second region resulted in an increase in volatiles and the growth of carbon domains. The final pore structure was achieved in the second region. The third region resulted in carbon domains increasing through the release of gases with heteroatoms.