A series of phenol-formaldehyde resins was produced in the presence of NaOH catalyst. Detailed structural and quantitative information was provided by C-13-NMR spectroscopy. The main interests were the relative quantities of bridge structures, methylol groups, and free phenol. Functionality and linearity of resins were also studied. The effects of the condensation F/P molar ratio on the structure and properties of the resins was studied by gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) in addition to C-13-NMR.